diff --git a/spec/integ/matrix-client-event-timeline.spec.ts b/spec/integ/matrix-client-event-timeline.spec.ts
index a520895160f..b02955511e9 100644
--- a/spec/integ/matrix-client-event-timeline.spec.ts
+++ b/spec/integ/matrix-client-event-timeline.spec.ts
@@ -1249,6 +1249,7 @@ describe("MatrixClient event timelines", function () {
                     },
                     event: true,
                 });
+                THREAD_REPLY2.localTimestamp += 1000;
 
                 // Test data for the first thread, with the second reply
                 const THREAD_ROOT_UPDATED = {
@@ -1305,6 +1306,7 @@ describe("MatrixClient event timelines", function () {
 
                 // Test adding a second event to the first thread
                 const thread = room.getThread(THREAD_ROOT.event_id!)!;
+                thread.initialEventsFetched = true;
                 const prom = emitPromise(room, ThreadEvent.NewReply);
                 respondToEvent(THREAD_ROOT_UPDATED);
                 respondToEvent(THREAD_ROOT_UPDATED);
@@ -1624,10 +1626,35 @@ describe("MatrixClient event timelines", function () {
                     },
                 },
             });
+            httpBackend
+                .when("GET", "/rooms/!foo%3Abar/event/" + encodeURIComponent(THREAD_ROOT.event_id!))
+                .respond(200, function () {
+                    return THREAD_ROOT;
+                });
+            httpBackend
+                .when("GET", "/rooms/!foo%3Abar/event/" + encodeURIComponent(THREAD_ROOT.event_id!))
+                .respond(200, function () {
+                    return THREAD_ROOT;
+                });
+            httpBackend
+                .when(
+                    "GET",
+                    "/_matrix/client/v1/rooms/!foo%3Abar/relations/" +
+                        encodeURIComponent(THREAD_ROOT.event_id!) +
+                        "/" +
+                        encodeURIComponent(THREAD_RELATION_TYPE.name) +
+                        buildRelationPaginationQuery({ dir: Direction.Backward, limit: 1 }),
+                )
+                .respond(200, function () {
+                    return {
+                        chunk: [THREAD_REPLY],
+                    };
+                });
             await Promise.all([httpBackend.flushAllExpected(), utils.syncPromise(client)]);
 
             const room = client.getRoom(roomId)!;
             const thread = room.getThread(THREAD_ROOT.event_id!)!;
+            expect(thread.initialEventsFetched).toBeTruthy();
             const timelineSet = thread.timelineSet;
 
             httpBackend
@@ -1645,6 +1672,28 @@ describe("MatrixClient event timelines", function () {
                 .respond(200, function () {
                     return THREAD_ROOT;
                 });
+            httpBackend
+                .when("GET", "/rooms/!foo%3Abar/event/" + encodeURIComponent(THREAD_ROOT.event_id!))
+                .respond(200, function () {
+                    return THREAD_ROOT;
+                });
+            httpBackend
+                .when("GET", "/rooms/!foo%3Abar/event/" + encodeURIComponent(THREAD_ROOT.event_id!))
+                .respond(200, function () {
+                    return THREAD_ROOT;
+                });
+            httpBackend
+                .when("GET", "/rooms/!foo%3Abar/context/" + encodeURIComponent(THREAD_ROOT.event_id!))
+                .respond(200, function () {
+                    return {
+                        start: "start_token",
+                        events_before: [],
+                        event: THREAD_ROOT,
+                        events_after: [],
+                        end: "end_token",
+                        state: [],
+                    };
+                });
             httpBackend
                 .when(
                     "GET",
@@ -1652,13 +1701,28 @@ describe("MatrixClient event timelines", function () {
                         encodeURIComponent(THREAD_ROOT.event_id!) +
                         "/" +
                         encodeURIComponent(THREAD_RELATION_TYPE.name) +
-                        buildRelationPaginationQuery({ dir: Direction.Backward, limit: 1 }),
+                        buildRelationPaginationQuery({ dir: Direction.Backward, from: "start_token" }),
                 )
                 .respond(200, function () {
                     return {
-                        chunk: [THREAD_ROOT],
+                        chunk: [],
                     };
                 });
+            httpBackend
+                .when(
+                    "GET",
+                    "/_matrix/client/v1/rooms/!foo%3Abar/relations/" +
+                        encodeURIComponent(THREAD_ROOT.event_id!) +
+                        "/" +
+                        encodeURIComponent(THREAD_RELATION_TYPE.name) +
+                        buildRelationPaginationQuery({ dir: Direction.Forward, from: "end_token" }),
+                )
+                .respond(200, function () {
+                    return {
+                        chunk: [THREAD_REPLY],
+                    };
+                });
+
             const timeline = await flushHttp(client.getEventTimeline(timelineSet, THREAD_ROOT.event_id!));
 
             httpBackend.when("GET", "/sync").respond(200, {
diff --git a/spec/unit/room.spec.ts b/spec/unit/room.spec.ts
index 5036cabaaf4..81f6602e784 100644
--- a/spec/unit/room.spec.ts
+++ b/spec/unit/room.spec.ts
@@ -29,6 +29,8 @@ import {
     EventTimelineSet,
     EventType,
     IContent,
+    IEvent,
+    IRelationsRequestOpts,
     IStateEventWithRoomId,
     JoinRule,
     MatrixEvent,
@@ -2489,11 +2491,24 @@ describe("Room", function () {
                     },
                 });
 
+            room.client.fetchRelations = (
+                roomId: string,
+                eventId: string,
+                relationType?: RelationType | string | null,
+                eventType?: EventType | string | null,
+                opts: IRelationsRequestOpts = { dir: Direction.Backward },
+            ) =>
+                Promise.resolve({
+                    chunk: [threadResponse.event] as IEvent[],
+                    next_batch: "start_token",
+                });
+
             let prom = emitPromise(room, ThreadEvent.New);
             room.addLiveEvents([randomMessage, threadRoot, threadResponse]);
             const thread: Thread = await prom;
             await emitPromise(room, ThreadEvent.Update);
 
+            expect(thread.initialEventsFetched).toBeTruthy();
             expect(thread.replyToEvent!.event).toEqual(threadResponse.event);
             expect(thread.replyToEvent!.getContent().body).toBe(threadResponse.getContent().body);
 
@@ -2704,13 +2719,27 @@ describe("Room", function () {
                     },
                 });
 
+            room.client.fetchRelations = (
+                roomId: string,
+                eventId: string,
+                relationType?: RelationType | string | null,
+                eventType?: EventType | string | null,
+                opts: IRelationsRequestOpts = { dir: Direction.Backward },
+            ) =>
+                Promise.resolve({
+                    chunk: [threadResponse1.event] as IEvent[],
+                    next_batch: "start_token",
+                });
+
             let prom = emitPromise(room, ThreadEvent.New);
-            room.addLiveEvents([threadRoot, threadResponse1, threadResponse2]);
-            const thread = await prom;
+            room.addLiveEvents([threadRoot, threadResponse1]);
+            const thread: Thread = await prom;
             await emitPromise(room, ThreadEvent.Update);
 
+            expect(thread.initialEventsFetched).toBeTruthy();
+            room.addLiveEvents([threadResponse2]);
             expect(thread).toHaveLength(2);
-            expect(thread.replyToEvent.getId()).toBe(threadResponse2.getId());
+            expect(thread.replyToEvent!.getId()).toBe(threadResponse2.getId());
 
             room.client.fetchRoomEvent = (eventId: string) =>
                 Promise.resolve({
@@ -2733,7 +2762,7 @@ describe("Room", function () {
             await prom;
             await emitPromise(room, ThreadEvent.Update);
             expect(thread).toHaveLength(1);
-            expect(thread.replyToEvent.getId()).toBe(threadResponse1.getId());
+            expect(thread.replyToEvent!.getId()).toBe(threadResponse1.getId());
 
             room.client.fetchRoomEvent = (eventId: string) =>
                 Promise.resolve({
@@ -2757,7 +2786,7 @@ describe("Room", function () {
             await prom;
             await prom2;
             expect(thread).toHaveLength(0);
-            expect(thread.replyToEvent.getId()).toBe(threadRoot.getId());
+            expect(thread.replyToEvent!.getId()).toBe(threadRoot.getId());
         });
     });
 
diff --git a/src/models/thread.ts b/src/models/thread.ts
index eaa62e27951..bca2d92b427 100644
--- a/src/models/thread.ts
+++ b/src/models/thread.ts
@@ -262,7 +262,7 @@ export class Thread extends ReadReceipt<EmittedEvents, EventHandlerMap> {
             this.addEventToTimeline(event, toStartOfTimeline);
 
             this.client.decryptEventIfNeeded(event, {});
-        } else if (!toStartOfTimeline && isNewestReply) {
+        } else if (!toStartOfTimeline && this.initialEventsFetched && isNewestReply) {
             this.addEventToTimeline(event, false);
             this.fetchEditsWhereNeeded(event);
         } else if (event.isRelation(RelationType.Annotation) || event.isRelation(RelationType.Replace)) {