diff --git a/src/domain/session/room/timeline/TilesCollection.js b/src/domain/session/room/timeline/TilesCollection.js
index 2a53c9d4..f8c55e3a 100644
--- a/src/domain/session/room/timeline/TilesCollection.js
+++ b/src/domain/session/room/timeline/TilesCollection.js
@@ -143,6 +143,10 @@ export class TilesCollection extends BaseObservableList {
     }
 
     onUpdate(index, entry, params) {
+        // if an update is emitted while calling source.subscribe() from onSubscribeFirst, ignore it
+        if (!this._tiles) {
+            return;
+        }
         const tileIdx = this._findTileIdx(entry);
         const tile = this._findTileAtIdx(entry, tileIdx);
         if (tile) {
diff --git a/src/observable/list/ConcatList.js b/src/observable/list/ConcatList.js
index a51ddd55..d395e807 100644
--- a/src/observable/list/ConcatList.js
+++ b/src/observable/list/ConcatList.js
@@ -33,10 +33,7 @@ export class ConcatList extends BaseObservableList {
     }
 
     onSubscribeFirst() {
-        this._sourceUnsubscribes = [];
-        for (const sourceList of this._sourceLists) {
-            this._sourceUnsubscribes.push(sourceList.subscribe(this));
-        }
+        this._sourceUnsubscribes = this._sourceLists.map(sourceList => sourceList.subscribe(this));
     }
 
     onUnsubscribeLast() {
@@ -62,6 +59,11 @@ export class ConcatList extends BaseObservableList {
     }
 
     onUpdate(index, value, params, sourceList) {
+        // if an update is emitted while calling source.subscribe() from onSubscribeFirst, ignore it
+        // as we are not supposed to call `length` on any uninitialized list
+        if (!this._sourceUnsubscribes) {
+            return;
+        }
         this.emitUpdate(this._offsetForSource(sourceList) + index, value, params);
     }
 
diff --git a/src/observable/list/MappedList.js b/src/observable/list/MappedList.js
index 0bc4065a..1aed299f 100644
--- a/src/observable/list/MappedList.js
+++ b/src/observable/list/MappedList.js
@@ -48,6 +48,10 @@ export class MappedList extends BaseObservableList {
     }
 
     onUpdate(index, value, params) {
+        // if an update is emitted while calling source.subscribe() from onSubscribeFirst, ignore it
+        if (!this._mappedValues) {
+            return;
+        }
         const mappedValue = this._mappedValues[index];
         if (this._updater) {
             this._updater(mappedValue, params, value);
diff --git a/src/observable/list/SortedMapList.js b/src/observable/list/SortedMapList.js
index 27003cba..babf5c35 100644
--- a/src/observable/list/SortedMapList.js
+++ b/src/observable/list/SortedMapList.js
@@ -70,6 +70,10 @@ export class SortedMapList extends BaseObservableList {
     }
 
     onUpdate(key, value, params) {
+        // if an update is emitted while calling source.subscribe() from onSubscribeFirst, ignore it
+        if (!this._sortedPairs) {
+            return;
+        }
         // TODO: suboptimal for performance, see above for idea with BST to speed this up if we need to
         const oldIdx = this._sortedPairs.findIndex(p => p.key === key);
         // neccesary to remove pair from array before
diff --git a/src/observable/map/FilteredMap.js b/src/observable/map/FilteredMap.js
index 71b7bbeb..8e936f5d 100644
--- a/src/observable/map/FilteredMap.js
+++ b/src/observable/map/FilteredMap.js
@@ -82,6 +82,10 @@ export class FilteredMap extends BaseObservableMap {
     }
 
     onUpdate(key, value, params) {
+        // if an update is emitted while calling source.subscribe() from onSubscribeFirst, ignore it
+        if (!this._included) {
+            return;
+        }
         if (this._filter) {
             const wasIncluded = this._included.get(key);
             const isIncluded = this._filter(value, key);
diff --git a/src/observable/map/JoinedMap.js b/src/observable/map/JoinedMap.js
index e5d0caa7..7db04be1 100644
--- a/src/observable/map/JoinedMap.js
+++ b/src/observable/map/JoinedMap.js
@@ -48,6 +48,10 @@ export class JoinedMap extends BaseObservableMap {
     }
 
     onUpdate(source, key, value, params) {
+        // if an update is emitted while calling source.subscribe() from onSubscribeFirst, ignore it
+        if (!this._subscriptions) {
+            return;
+        }
         if (!this._isKeyAtSourceOccluded(source, key)) {
             this.emitUpdate(key, value, params);
         }
diff --git a/src/observable/map/MappedMap.js b/src/observable/map/MappedMap.js
index 48a1d1ad..ec33c4dd 100644
--- a/src/observable/map/MappedMap.js
+++ b/src/observable/map/MappedMap.js
@@ -49,6 +49,10 @@ export class MappedMap extends BaseObservableMap {
     }
 
     onUpdate(key, value, params) {
+        // if an update is emitted while calling source.subscribe() from onSubscribeFirst, ignore it
+        if (!this._mappedValues) {
+            return;
+        }
         const mappedValue = this._mappedValues.get(key);
         if (mappedValue !== undefined) {
             // TODO: map params somehow if needed?