diff --git a/apps/client/src/common/utils/eventsManager.ts b/apps/client/src/common/utils/eventsManager.ts
index 468c4d931..b16288296 100644
--- a/apps/client/src/common/utils/eventsManager.ts
+++ b/apps/client/src/common/utils/eventsManager.ts
@@ -24,6 +24,7 @@ export const cloneEvent = (event: OntimeEvent): ClonedEvent => {
     skip: event.skip,
     colour: event.colour,
     revision: 0,
+    delay: 0,
     timeWarning: event.timeWarning,
     timeDanger: event.timeDanger,
     custom: {},
diff --git a/apps/server/src/classes/data-provider/DataProvider.ts b/apps/server/src/classes/data-provider/DataProvider.ts
index 5dc6fdea2..07ffe31d6 100644
--- a/apps/server/src/classes/data-provider/DataProvider.ts
+++ b/apps/server/src/classes/data-provider/DataProvider.ts
@@ -86,7 +86,7 @@ function getCustomFields(): Readonly<CustomFields> {
 }
 
 async function setRundown(newData: OntimeRundown): ReadonlyPromise<OntimeRundown> {
-  db.data.rundown = [...newData];
+  db.data.rundown = newData;
   await persist();
   return db.data.rundown;
 }
diff --git a/apps/server/src/classes/data-provider/__tests__/DataProvider.utils.test.ts b/apps/server/src/classes/data-provider/__tests__/DataProvider.utils.test.ts
index 5315fc833..c95647c2d 100644
--- a/apps/server/src/classes/data-provider/__tests__/DataProvider.utils.test.ts
+++ b/apps/server/src/classes/data-provider/__tests__/DataProvider.utils.test.ts
@@ -143,6 +143,7 @@ describe('safeMerge', () => {
         publicInfo: '',
         backstageUrl: '',
         backstageInfo: '',
+        projectLogo: null,
       },
       settings: {
         app: 'ontime',
diff --git a/apps/server/src/models/demoProject.ts b/apps/server/src/models/demoProject.ts
index 0733e0a2d..0de02ef79 100644
--- a/apps/server/src/models/demoProject.ts
+++ b/apps/server/src/models/demoProject.ts
@@ -20,6 +20,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -45,6 +46,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -70,6 +72,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -95,6 +98,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -120,6 +124,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -150,6 +155,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -175,6 +181,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -200,6 +207,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -225,6 +233,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -250,6 +259,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -280,6 +290,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -305,6 +316,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -330,6 +342,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
@@ -355,6 +368,7 @@ export const demoDb: DatabaseModel = {
       skip: false,
       colour: '',
       revision: 0,
+      delay: 0,
       timeWarning: 500000,
       timeDanger: 100000,
       custom: {
diff --git a/apps/server/src/models/eventsDefinition.ts b/apps/server/src/models/eventsDefinition.ts
index 40b7a4650..6a10ede10 100644
--- a/apps/server/src/models/eventsDefinition.ts
+++ b/apps/server/src/models/eventsDefinition.ts
@@ -8,7 +8,7 @@ import {
   TimerType,
 } from 'ontime-types';
 
-export const event: Omit<OntimeEvent, 'id' | 'delay' | 'cue'> = {
+export const event: Omit<OntimeEvent, 'id' | 'cue'> = {
   title: '',
   note: '',
   endAction: EndAction.None,
@@ -24,6 +24,7 @@ export const event: Omit<OntimeEvent, 'id' | 'delay' | 'cue'> = {
   colour: '',
   type: SupportedEvent.Event,
   revision: 0,
+  delay: 0,
   timeWarning: 120000,
   timeDanger: 60000,
   custom: {},
diff --git a/apps/server/src/services/rundown-service/__tests__/rundownCache.test.ts b/apps/server/src/services/rundown-service/__tests__/rundownCache.test.ts
index dc7dced1d..f7a7b58b3 100644
--- a/apps/server/src/services/rundown-service/__tests__/rundownCache.test.ts
+++ b/apps/server/src/services/rundown-service/__tests__/rundownCache.test.ts
@@ -438,7 +438,7 @@ describe('add() mutation', () => {
   test('adds an event to the rundown', () => {
     const mockEvent = { id: 'mock', cue: 'mock', type: SupportedEvent.Event } as OntimeEvent;
     const testRundown: OntimeRundown = [];
-    const { newRundown } = add({ atIndex: 0, event: mockEvent, persistedRundown: testRundown });
+    const { newRundown } = add({ atIndex: 0, event: mockEvent, rundown: testRundown });
     expect(newRundown.length).toBe(1);
     expect(newRundown[0]).toMatchObject(mockEvent);
   });
@@ -448,7 +448,7 @@ describe('remove() mutation', () => {
   test('deletes an event from the rundown', () => {
     const mockEvent = { id: 'mock', cue: 'mock', type: SupportedEvent.Event } as OntimeEvent;
     const testRundown: OntimeRundown = [mockEvent];
-    const { newRundown } = remove({ eventIds: [mockEvent.id], persistedRundown: testRundown });
+    const { newRundown } = remove({ eventIds: [mockEvent.id], rundown: testRundown });
     expect(newRundown.length).toBe(0);
   });
   test('deletes multiple events from the rundown', () => {
@@ -460,7 +460,7 @@ describe('remove() mutation', () => {
       { type: SupportedEvent.Event, id: '5' } as OntimeEvent,
       { type: SupportedEvent.Event, id: '6' } as OntimeEvent,
     ];
-    const { newRundown } = remove({ eventIds: ['1', '2', '3'], persistedRundown: testRundown });
+    const { newRundown } = remove({ eventIds: ['1', '2', '3'], rundown: testRundown });
     expect(newRundown.length).toBe(3);
     expect(newRundown.at(0)?.id).toBe('4');
   });
@@ -474,7 +474,7 @@ describe('edit() mutation', () => {
     const { newRundown, newEvent } = edit({
       eventId: mockEvent.id,
       patch: mockEventPatch,
-      persistedRundown: testRundown,
+      rundown: testRundown,
     });
     expect(newRundown.length).toBe(1);
     expect(newEvent).toMatchObject({
@@ -487,7 +487,7 @@ describe('edit() mutation', () => {
 
 describe('batchEdit() mutation', () => {
   it('should correctly apply the patch to the events with the given IDs', () => {
-    const persistedRundown: OntimeRundown = [
+    const testRundown: OntimeRundown = [
       { id: '1', type: SupportedEvent.Event, cue: 'data1' } as OntimeEvent,
       { id: '2', type: SupportedEvent.Event, cue: 'data2' } as OntimeEvent,
       { id: '3', type: SupportedEvent.Event, cue: 'data3' } as OntimeEvent,
@@ -495,7 +495,7 @@ describe('batchEdit() mutation', () => {
     const eventIds = ['1', '3'];
     const patch = { cue: 'newData' };
 
-    const { newRundown } = batchEdit({ persistedRundown, eventIds, patch });
+    const { newRundown } = batchEdit({ rundown: testRundown, eventIds, patch });
 
     expect(newRundown).toMatchObject([
       { id: '1', type: SupportedEvent.Event, cue: 'newData' },
@@ -507,16 +507,16 @@ describe('batchEdit() mutation', () => {
 
 describe('reorder() mutation', () => {
   it('should correctly reorder two events', () => {
-    const persistedRundown: OntimeRundown = [
+    const testRundown: OntimeRundown = [
       { id: '1', type: SupportedEvent.Event, cue: 'data1', revision: 0 } as OntimeEvent,
       { id: '2', type: SupportedEvent.Event, cue: 'data2', revision: 0 } as OntimeEvent,
       { id: '3', type: SupportedEvent.Event, cue: 'data3', revision: 0 } as OntimeEvent,
     ];
     const { newRundown } = reorder({
-      persistedRundown,
-      eventId: persistedRundown[0].id,
+      rundown: testRundown,
+      eventId: testRundown[0].id,
       from: 0,
-      to: persistedRundown.length - 1,
+      to: testRundown.length - 1,
     });
 
     expect(newRundown).toMatchObject([
@@ -529,15 +529,15 @@ describe('reorder() mutation', () => {
 
 describe('swap() mutation', () => {
   it('should correctly swap data between events', () => {
-    const persistedRundown: OntimeRundown = [
+    const testRundown: OntimeRundown = [
       { id: '1', type: SupportedEvent.Event, cue: 'data1', timeStart: 1, revision: 0 } as OntimeEvent,
       { id: '2', type: SupportedEvent.Event, cue: 'data2', timeStart: 2, revision: 0 } as OntimeEvent,
       { id: '3', type: SupportedEvent.Event, cue: 'data3', timeStart: 3, revision: 0 } as OntimeEvent,
     ];
     const { newRundown } = swap({
-      persistedRundown,
-      fromId: persistedRundown[0].id,
-      toId: persistedRundown[1].id,
+      rundown: testRundown,
+      fromId: testRundown[0].id,
+      toId: testRundown[1].id,
     });
 
     expect((newRundown[0] as OntimeEvent).id).toBe('1');
@@ -576,6 +576,7 @@ describe('calculateRuntimeDelays', () => {
         colour: '',
         type: SupportedEvent.Event,
         revision: 0,
+        delay: 0,
         timeWarning: 120000,
         timeDanger: 60000,
         id: '659e1',
@@ -603,6 +604,7 @@ describe('calculateRuntimeDelays', () => {
         colour: '',
         type: SupportedEvent.Event,
         revision: 0,
+        delay: 0,
         timeWarning: 120000,
         timeDanger: 60000,
         id: '1c48f',
@@ -630,6 +632,7 @@ describe('calculateRuntimeDelays', () => {
         colour: '',
         type: SupportedEvent.Event,
         revision: 0,
+        delay: 0,
         timeWarning: 120000,
         timeDanger: 60000,
         id: 'd48c2',
@@ -657,6 +660,7 @@ describe('calculateRuntimeDelays', () => {
         colour: '',
         type: SupportedEvent.Event,
         revision: 0,
+        delay: 0,
         timeWarning: 120000,
         timeDanger: 60000,
         id: '2f185',
@@ -935,7 +939,7 @@ describe('calculateRuntimeDelaysFrom()', () => {
 
 describe('custom fields', () => {
   describe('createCustomField()', () => {
-    it('creates a field from given parameters', async () => {
+    it('creates a field from given parameters', () => {
       const expected = {
         Lighting: {
           label: 'Lighting',
@@ -944,14 +948,14 @@ describe('custom fields', () => {
         },
       };
 
-      const customField = await createCustomField({ label: 'Lighting', type: 'string', colour: 'blue' });
+      const customField = createCustomField({ label: 'Lighting', type: 'string', colour: 'blue' });
       expect(customField).toStrictEqual(expected);
     });
   });
 
   describe('editCustomField()', () => {
-    it('edits a field with a given label', async () => {
-      await createCustomField({ label: 'Sound', type: 'string', colour: 'blue' });
+    it('edits a field with a given label', () => {
+      createCustomField({ label: 'Sound', type: 'string', colour: 'blue' });
 
       const expected = {
         Lighting: {
@@ -966,14 +970,14 @@ describe('custom fields', () => {
         },
       };
 
-      const customField = await editCustomField('Sound', { label: 'Sound', type: 'string', colour: 'green' });
+      const customField = editCustomField('Sound', { label: 'Sound', type: 'string', colour: 'green' });
       expect(customFieldChangelog).toStrictEqual(new Map());
 
       expect(customField).toStrictEqual(expected);
     });
 
-    it('renames a field to a new label', async () => {
-      const created = await createCustomField({ label: 'Video', type: 'string', colour: 'red' });
+    it('renames a field to a new label', () => {
+      const created = createCustomField({ label: 'Video', type: 'string', colour: 'red' });
 
       const expected = {
         Lighting: {
@@ -1015,10 +1019,10 @@ describe('custom fields', () => {
 
       // We need to flush all scheduled tasks for the generate function to settle
       vi.useFakeTimers();
-      const customField = await editCustomField('Video', { label: 'AV', type: 'string', colour: 'red' });
+      const customField = editCustomField('Video', { label: 'AV', type: 'string', colour: 'red' });
       expect(customField).toStrictEqual(expectedAfter);
       expect(customFieldChangelog).toStrictEqual(new Map([['Video', 'AV']]));
-      await editCustomField('AV', { label: 'Video' });
+      editCustomField('AV', { label: 'Video' });
       vi.runAllTimers();
       expect(customFieldChangelog).toStrictEqual(new Map());
       vi.useRealTimers();
@@ -1026,7 +1030,7 @@ describe('custom fields', () => {
   });
 
   describe('removeCustomField()', () => {
-    it('deletes a field with a given label', async () => {
+    it('deletes a field with a given label', () => {
       const expected = {
         Lighting: {
           label: 'Lighting',
@@ -1040,7 +1044,7 @@ describe('custom fields', () => {
         },
       };
 
-      const customField = await removeCustomField('Sound');
+      const customField = removeCustomField('Sound');
 
       expect(customField).toStrictEqual(expected);
     });
diff --git a/apps/server/src/services/rundown-service/rundownCache.ts b/apps/server/src/services/rundown-service/rundownCache.ts
index 448c9c7b2..9ffd5c71d 100644
--- a/apps/server/src/services/rundown-service/rundownCache.ts
+++ b/apps/server/src/services/rundown-service/rundownCache.ts
@@ -2,6 +2,7 @@ import {
   CustomField,
   CustomFieldLabel,
   CustomFields,
+  isOntimeBlock,
   isOntimeDelay,
   isOntimeEvent,
   isPlayableEvent,
@@ -31,14 +32,27 @@ type NormalisedRundown = Record<EventID, OntimeRundownEntry>;
 let persistedRundown: OntimeRundown = [];
 let persistedCustomFields: CustomFields = {};
 
-/** Utility function gets to expose data */
+/**
+ * Get the cached rundown without triggering regeneration
+ */
 export const getPersistedRundown = (): OntimeRundown => persistedRundown;
 export const getCustomFields = (): CustomFields => persistedCustomFields;
 
-let rundown: NormalisedRundown = {};
+let normalisedRundown: NormalisedRundown = {};
 let order: EventID[] = [];
 let revision = 0;
+
+/**
+ * all mutating functions will set this value if there is a need for re-generation
+ * but will only be cleared by the generate function
+ */
 let isStale = true;
+
+/** Allows safely setting the stale state without accidentally clearing it */
+function setIsStale() {
+  isStale = true;
+}
+
 let totalDelay = 0;
 let totalDuration = 0;
 let firstStart: MaybeNumber = null;
@@ -72,18 +86,22 @@ export async function init(initialRundown: Readonly<OntimeRundown>, customFields
 }
 
 /**
- * Utility initialises cache
- * @param rundown
+ * Utility generate cache
+ * @private should not be called outside of `rundownCache.ts`
  */
 export function generate(
   initialRundown: OntimeRundown = persistedRundown,
   customFields: CustomFields = persistedCustomFields,
 ) {
+  function clearIsStale() {
+    isStale = false;
+  }
+
   // we decided to re-write this dataset for every change
   // instead of maintaining logic to update it
 
   assignedCustomFields = {};
-  rundown = {};
+  normalisedRundown = {};
   order = [];
   links = {};
   firstStart = null;
@@ -94,11 +112,12 @@ export function generate(
   let lastEntry: PlayableEvent | null = null;
 
   for (let i = 0; i < initialRundown.length; i++) {
-    // TODO: filter properties that should not be persisted (eg: delay)
     // we assign a reference to the current entry, this will be mutated in place
     const currentEntry = initialRundown[i];
 
     if (isOntimeEvent(currentEntry)) {
+      currentEntry.delay = 0;
+
       // 1. handle links - mutates updatedEvent
       handleLink(i, initialRundown, currentEntry, links);
 
@@ -145,24 +164,30 @@ export function generate(
           lastEntry = currentEntry;
         }
       }
-    }
-
-    // calculate delays
-    // !!! this must happen after handling the links
-    if (isOntimeDelay(currentEntry)) {
+    } else if (isOntimeDelay(currentEntry)) {
+      // calculate delays
+      // !!! this must happen after handling the links
       totalDelay += currentEntry.duration;
+    } else if (isOntimeBlock(currentEntry)) {
+      // calculate block - nothing yet
+    } else {
+      // unknown - type skip it
+      // this is needed to get the type guard working when we assign the entry to the rundown
+      continue;
     }
 
     // add id to order
     order.push(currentEntry.id);
     // add entry to rundown
-    rundown[currentEntry.id] = currentEntry;
+    normalisedRundown[currentEntry.id] = currentEntry;
   }
 
   lastEnd = lastEntry?.timeEnd ?? null;
-  isStale = false;
+  clearIsStale();
   customFieldChangelog.clear();
-  return { rundown, order, links, totalDelay, totalDuration, assignedCustomFields };
+
+  //The return value is used for testing
+  return { rundown: normalisedRundown, order, links, totalDelay, totalDuration, assignedCustomFields };
 }
 
 /** Returns an ID guaranteed to be unique */
@@ -173,7 +198,7 @@ export function getUniqueId(): string {
   let id = '';
   do {
     id = generateId();
-  } while (Object.hasOwn(rundown, id));
+  } while (Object.hasOwn(normalisedRundown, id));
   return id;
 }
 
@@ -194,15 +219,15 @@ type RundownCache = {
 };
 
 /**
- * Returns cached data
- * @returns {RundownCache}
+ * Returns the full rundown cache.
+ * Will triggering regeneration if data is stale.
  */
 export function get(): Readonly<RundownCache> {
   if (isStale) {
     generate();
   }
   return {
-    rundown,
+    rundown: normalisedRundown,
     order,
     revision,
     totalDelay,
@@ -212,6 +237,7 @@ export function get(): Readonly<RundownCache> {
 
 /**
  * Returns calculated metadata from rundown
+ * Will triggering regeneration if data is stale.
  */
 export function getMetadata() {
   if (isStale) {
@@ -227,7 +253,7 @@ export function getMetadata() {
   };
 }
 
-type CommonParams = { persistedRundown: OntimeRundown };
+type CommonParams = { rundown: OntimeRundown };
 type MutationParams<T> = T & CommonParams;
 type MutatingReturn = {
   newRundown: OntimeRundown;
@@ -238,23 +264,14 @@ type MutatingFn<T extends object> = (params: MutationParams<T>) => MutatingRetur
 
 /**
  * Decorators injects data into mutation
- * @param mutation
- * @returns
+ * ensures order of operations when performing mutations
  */
 export function mutateCache<T extends object>(mutation: MutatingFn<T>) {
-  async function scopedMutation(params: T) {
-    /**
-     * Marking the data set as stale
-     * doing it before calling the mutation, gives the function a chance
-     * to prevent recalculation by setting stale = false
-     */
-    isStale = true;
-
-    const { newEvent, newRundown, didMutate } = mutation({ ...params, persistedRundown });
+  function scopedMutation(params: T) {
+    const { newEvent, newRundown, didMutate } = mutation({ ...params, rundown: persistedRundown });
 
     // early return without calling side effects
     if (!didMutate) {
-      isStale = false;
       return { newEvent, newRundown, didMutate };
     }
 
@@ -278,31 +295,34 @@ export function mutateCache<T extends object>(mutation: MutatingFn<T>) {
 }
 
 type AddArgs = MutationParams<{ atIndex: number; event: OntimeRundownEntry }>;
-
-export function add({ persistedRundown, atIndex, event }: AddArgs): Required<MutatingReturn> {
+/**
+ * Add entry to rundown
+ */
+export function add({ rundown, atIndex, event }: AddArgs): Required<MutatingReturn> {
   const newEvent: OntimeRundownEntry = { ...event };
-  const newRundown = insertAtIndex(atIndex, newEvent, persistedRundown);
-
+  const newRundown = insertAtIndex(atIndex, newEvent, rundown);
+  setIsStale();
   return { newRundown, newEvent, didMutate: true };
 }
 
 type RemoveArgs = MutationParams<{ eventIds: string[] }>;
-
-export function remove({ persistedRundown, eventIds }: RemoveArgs): MutatingReturn {
-  const newRundown = persistedRundown.filter((event) => !eventIds.includes(event.id));
-
-  return { newRundown, didMutate: persistedRundown.length !== newRundown.length };
+/**
+ * Remove entry to rundown
+ */
+export function remove({ rundown, eventIds }: RemoveArgs): MutatingReturn {
+  const newRundown = rundown.filter((event) => !eventIds.includes(event.id));
+  const didMutate = rundown.length !== newRundown.length;
+  if (didMutate) setIsStale();
+  return { newRundown, didMutate };
 }
 
 export function removeAll(): MutatingReturn {
+  setIsStale();
   return { newRundown: [], didMutate: true };
 }
 
 /**
- * Utility function for patching events
- * @param eventFromRundown
- * @param patch
- * @returns
+ * Utility function for patching an existing event with new data
  */
 function makeEvent(eventFromRundown: OntimeRundownEntry, patch: Partial<OntimeRundownEntry>): OntimeRundownEntry {
   if (isOntimeEvent(eventFromRundown)) {
@@ -315,120 +335,133 @@ function makeEvent(eventFromRundown: OntimeRundownEntry, patch: Partial<OntimeRu
 }
 
 type EditArgs = MutationParams<{ eventId: string; patch: Partial<OntimeRundownEntry> }>;
-
-export function edit({ persistedRundown, eventId, patch }: EditArgs): Required<MutatingReturn> {
-  const indexAt = persistedRundown.findIndex((event) => event.id === eventId);
-
+/**
+ * Apply patch to an entry with given id
+ */
+export function edit({ rundown, eventId, patch }: EditArgs): Required<MutatingReturn> {
+  const indexAt = rundown.findIndex((event) => event.id === eventId);
   if (indexAt < 0) {
     throw new Error('Event not found');
   }
 
-  if (patch?.type && persistedRundown[indexAt].type !== patch.type) {
+  if (patch?.type && rundown[indexAt].type !== patch.type) {
     throw new Error('Invalid event type');
   }
 
-  const eventInMemory = persistedRundown[indexAt];
+  const eventInMemory = rundown[indexAt];
+
   if (!hasChanges(eventInMemory, patch)) {
-    isStale = false;
-    return { newRundown: persistedRundown, newEvent: eventInMemory, didMutate: false };
+    return { newRundown: rundown, newEvent: eventInMemory, didMutate: false };
   }
 
   const newEvent = makeEvent(eventInMemory, patch);
 
-  const newRundown = [...persistedRundown];
+  const newRundown = [...rundown];
   newRundown[indexAt] = newEvent;
 
   // check whether the data warrants recalculation of cache
   const makeStale = isDataStale(patch);
 
-  if (!makeStale) {
-    rundown[newEvent.id] = newEvent;
+  if (makeStale) {
+    setIsStale();
+  } else {
+    normalisedRundown[newEvent.id] = newEvent;
   }
 
-  isStale = makeStale;
   return { newRundown, newEvent, didMutate: true };
 }
 
 type BatchEditArgs = MutationParams<{ eventIds: string[]; patch: Partial<OntimeRundownEntry> }>;
-
-export function batchEdit({ persistedRundown, eventIds, patch }: BatchEditArgs): MutatingReturn {
+/**
+ * Apply patch to multiple entries
+ */
+export function batchEdit({ rundown, eventIds, patch }: BatchEditArgs): MutatingReturn {
   const ids = new Set(eventIds);
 
   const newRundown = [];
-  for (let i = 0; i < persistedRundown.length; i++) {
-    if (ids.has(persistedRundown[i].id)) {
-      if (patch?.type && persistedRundown[i].type !== patch.type) {
+  for (let i = 0; i < rundown.length; i++) {
+    if (ids.has(rundown[i].id)) {
+      if (patch?.type && rundown[i].type !== patch.type) {
         continue;
       }
-      const newEvent = makeEvent(persistedRundown[i], patch);
+      const newEvent = makeEvent(rundown[i], patch);
       newRundown.push(newEvent);
     } else {
-      newRundown.push(persistedRundown[i]);
+      newRundown.push(rundown[i]);
     }
   }
+  setIsStale();
   return { newRundown, didMutate: true };
 }
 
 type ReorderArgs = MutationParams<{ eventId: string; from: number; to: number }>;
-
-export function reorder({ persistedRundown, eventId, from, to }: ReorderArgs): Required<MutatingReturn> {
-  const event = persistedRundown[from];
+/**
+ * Redorder two entries
+ */
+export function reorder({ rundown, eventId, from, to }: ReorderArgs): Required<MutatingReturn> {
+  const event = rundown[from];
   if (!event || eventId !== event.id) {
     throw new Error('Event not found');
   }
 
-  const newRundown = reorderArray(persistedRundown, from, to);
+  const newRundown = reorderArray(rundown, from, to);
   for (let i = from; i <= to; i++) {
     const event = newRundown.at(i);
     if (isOntimeEvent(event)) {
       event.revision += 1;
     }
   }
+  setIsStale();
   return { newRundown, newEvent: newRundown.at(from) as OntimeRundownEntry, didMutate: true };
 }
 
 type ApplyDelayArgs = MutationParams<{ eventId: string }>;
-
-export function applyDelay({ persistedRundown, eventId }: ApplyDelayArgs): MutatingReturn {
-  const newRundown = apply(eventId, persistedRundown);
+/**
+ * Apply a delay
+ */
+export function applyDelay({ rundown, eventId }: ApplyDelayArgs): MutatingReturn {
+  const newRundown = apply(eventId, rundown);
+  setIsStale();
   return { newRundown, didMutate: true };
 }
 
 type SwapArgs = MutationParams<{ fromId: string; toId: string }>;
+/**
+ * Swap two entries
+ */
+export function swap({ rundown, fromId, toId }: SwapArgs): MutatingReturn {
+  const indexA = rundown.findIndex((event) => event.id === fromId);
+  const eventA = rundown.at(indexA);
 
-export function swap({ persistedRundown, fromId, toId }: SwapArgs): MutatingReturn {
-  const indexA = persistedRundown.findIndex((event) => event.id === fromId);
-  const eventA = persistedRundown.at(indexA);
-
-  const indexB = persistedRundown.findIndex((event) => event.id === toId);
-  const eventB = persistedRundown.at(indexB);
+  const indexB = rundown.findIndex((event) => event.id === toId);
+  const eventB = rundown.at(indexB);
 
   if (!isOntimeEvent(eventA) || !isOntimeEvent(eventB)) {
     throw new Error('Swap only available for OntimeEvents');
   }
 
   const { newA, newB } = swapEventData(eventA, eventB);
-  const newRundown = [...persistedRundown];
+  const newRundown = [...rundown];
 
   newRundown[indexA] = newA;
   (newRundown[indexA] as OntimeEvent).revision += 1;
   newRundown[indexB] = newB;
   (newRundown[indexB] as OntimeEvent).revision += 1;
 
+  setIsStale();
   return { newRundown, didMutate: true };
 }
 
 /**
- * Invalidates service cache if a custom field is used
- * @param label
+ * Utility for invalidating service cache if a custom field is used
  */
 function invalidateIfUsed(label: CustomFieldLabel) {
   if (label in assignedCustomFields) {
-    isStale = true;
+    setIsStale();
   }
   // if the field was in use, we mark the cache as stale
   if (label in assignedCustomFields) {
-    isStale = true;
+    setIsStale();
   }
   // ... and schedule a cache update
   // schedule a non priority cache update
@@ -439,10 +472,9 @@ function invalidateIfUsed(label: CustomFieldLabel) {
 }
 
 /**
- * Schedules a non priority custom field persist
- * @param persistedCustomFields
+ * Utility for scheduling a non priority custom field persist
  */
-function scheduleCustomFieldPersist(persistedCustomFields: CustomFields) {
+function scheduleCustomFieldPersist() {
   setImmediate(async () => {
     await getDataProvider().setCustomFields(persistedCustomFields);
   });
@@ -450,12 +482,15 @@ function scheduleCustomFieldPersist(persistedCustomFields: CustomFields) {
 
 /**
  * Sanitises and creates a custom field in the database
- * @param field
- * @returns
  */
-export const createCustomField = async (field: CustomField) => {
+export function createCustomField(field: CustomField): CustomFields {
   const { label, type, colour } = field;
   const key = customFieldLabelToKey(label);
+
+  if (key === null) {
+    throw new Error('Unable to convert label to a valid key');
+  }
+
   // check if label already exists
   const alreadyExists = Object.hasOwn(persistedCustomFields, key);
 
@@ -466,18 +501,15 @@ export const createCustomField = async (field: CustomField) => {
   // update object and persist
   persistedCustomFields[key] = { label, type, colour };
 
-  scheduleCustomFieldPersist(persistedCustomFields);
+  scheduleCustomFieldPersist();
 
   return persistedCustomFields;
-};
+}
 
 /**
  * Edits an existing custom field in the database
- * @param key
- * @param newField
- * @returns
  */
-export const editCustomField = async (key: string, newField: Partial<CustomField>) => {
+export function editCustomField(key: string, newField: Partial<CustomField>): CustomFields {
   if (!(key in persistedCustomFields)) {
     throw new Error('Could not find label');
   }
@@ -487,7 +519,14 @@ export const editCustomField = async (key: string, newField: Partial<CustomField
     throw new Error('Change of field type is not allowed');
   }
 
+  if (newField.label === undefined) {
+    throw new Error('Missing label');
+  }
+
   const newKey = customFieldLabelToKey(newField.label);
+  if (newKey === null) {
+    throw new Error('Unable to convert label to a valid key');
+  }
   persistedCustomFields[newKey] = { ...existingField, ...newField };
 
   if (key !== newKey) {
@@ -495,23 +534,22 @@ export const editCustomField = async (key: string, newField: Partial<CustomField
     customFieldChangelog.set(key, newKey);
   }
 
-  scheduleCustomFieldPersist(persistedCustomFields);
+  scheduleCustomFieldPersist();
   invalidateIfUsed(key);
 
   return persistedCustomFields;
-};
+}
 
 /**
  * Deletes a custom field from the database
- * @param label
  */
-export const removeCustomField = async (label: string) => {
+export function removeCustomField(label: string): CustomFields {
   if (label in persistedCustomFields) {
     delete persistedCustomFields[label];
   }
 
-  scheduleCustomFieldPersist(persistedCustomFields);
+  scheduleCustomFieldPersist();
   invalidateIfUsed(label);
 
   return persistedCustomFields;
-};
+}
diff --git a/apps/server/src/services/rundown-service/rundownCacheUtils.ts b/apps/server/src/services/rundown-service/rundownCacheUtils.ts
index 8e8a1ab66..28488ab8d 100644
--- a/apps/server/src/services/rundown-service/rundownCacheUtils.ts
+++ b/apps/server/src/services/rundown-service/rundownCacheUtils.ts
@@ -86,7 +86,7 @@ export function handleCustomField(
     // rename the property if it is in the changelog
     if (customFieldChangelog.has(field)) {
       const oldData = mutableEvent.custom[field];
-      const newLabel = customFieldChangelog.get(field);
+      const newLabel = customFieldChangelog.get(field) as string; // it os OK to cast to string here since we already checked that it existed
 
       mutableEvent.custom[newLabel] = oldData;
       delete mutableEvent.custom[field];
@@ -143,6 +143,6 @@ export function willCauseRegeneration(key: keyof OntimeEvent): boolean {
  */
 export function hasChanges<T extends OntimeBaseEvent>(existingEvent: T, newEvent: Partial<T>): boolean {
   return Object.keys(newEvent).some(
-    (key) => !Object.hasOwn(existingEvent, key) || existingEvent[key] !== newEvent[key],
+    (key) => !Object.hasOwn(existingEvent, key) || existingEvent[key as keyof T] !== newEvent[key as keyof T],
   );
 }
diff --git a/apps/server/src/services/sheet-service/__tests__/sheetUtils.test.ts b/apps/server/src/services/sheet-service/__tests__/sheetUtils.test.ts
index 0e7ed8565..5ccd6cffd 100644
--- a/apps/server/src/services/sheet-service/__tests__/sheetUtils.test.ts
+++ b/apps/server/src/services/sheet-service/__tests__/sheetUtils.test.ts
@@ -36,6 +36,7 @@ describe('cellRequestFromEvent()', () => {
       isPublic: false,
       skip: false,
       colour: 'red',
+      delay: 0,
       revision: 0,
       id: '1358',
       timeWarning: 0,
@@ -82,6 +83,7 @@ describe('cellRequestFromEvent()', () => {
       skip: false,
       colour: 'red',
       revision: 0,
+      delay: 0,
       id: '1358',
       timeWarning: 0,
       timeDanger: 0,
@@ -129,6 +131,7 @@ describe('cellRequestFromEvent()', () => {
       skip: false,
       colour: 'red',
       revision: 0,
+      delay: 0,
       id: '1358',
       timeWarning: 0,
       timeDanger: 0,
@@ -174,6 +177,7 @@ describe('cellRequestFromEvent()', () => {
       isPublic: true,
       skip: false,
       colour: 'red',
+      delay: 0,
       revision: 0,
       id: '1358',
       timeWarning: 0,
@@ -207,6 +211,7 @@ describe('cellRequestFromEvent()', () => {
       skip: false,
       colour: 'red',
       revision: 0,
+      delay: 0,
       id: '1358',
       timeWarning: 0,
       timeDanger: 0,
@@ -240,6 +245,7 @@ describe('cellRequestFromEvent()', () => {
       skip: false,
       colour: 'red',
       revision: 0,
+      delay: 0,
       id: '1358',
       timeWarning: 0,
       timeDanger: 0,
diff --git a/apps/server/src/utils/parser.ts b/apps/server/src/utils/parser.ts
index 102230f4e..3caf5e311 100644
--- a/apps/server/src/utils/parser.ts
+++ b/apps/server/src/utils/parser.ts
@@ -384,6 +384,7 @@ export function createPatch(originalEvent: OntimeEvent, patchEvent: Partial<Onti
     skip: typeof patchEvent.skip === 'boolean' ? patchEvent.skip : originalEvent.skip,
     note: makeString(patchEvent.note, originalEvent.note),
     colour: makeString(patchEvent.colour, originalEvent.colour),
+    delay: 0, //delay is always regenerated by the cache
     // short circuit empty string
     cue: makeString(patchEvent.cue ?? null, originalEvent.cue),
     revision: originalEvent.revision,
diff --git a/packages/types/src/definitions/core/OntimeEvent.type.ts b/packages/types/src/definitions/core/OntimeEvent.type.ts
index 9d68739ff..02f1ce225 100644
--- a/packages/types/src/definitions/core/OntimeEvent.type.ts
+++ b/packages/types/src/definitions/core/OntimeEvent.type.ts
@@ -38,7 +38,7 @@ export type OntimeEvent = OntimeBaseEvent & {
   skip: boolean;
   colour: string;
   revision: number;
-  delay?: number; // calculated at runtime
+  delay: number; // calculated at runtime
   timeWarning: number;
   timeDanger: number;
   custom: EventCustomFields;
diff --git a/packages/utils/src/customField-utils/customFieldLabelToKey.ts b/packages/utils/src/customField-utils/customFieldLabelToKey.ts
index fd56e29dc..63aab28cd 100644
--- a/packages/utils/src/customField-utils/customFieldLabelToKey.ts
+++ b/packages/utils/src/customField-utils/customFieldLabelToKey.ts
@@ -2,7 +2,6 @@ import { isAlphanumericWithSpace } from '../regex-utils/isAlphanumeric.js';
 
 /**
  * @description Transforms a Custom field label into a valid key or returns null if not possible
- * @returns {string | null}
  */
 export const customFieldLabelToKey = (label: string): string | null => {
   if (isAlphanumericWithSpace(label)) {