diff --git a/src/app/features/room/ThreadBrowser.tsx b/src/app/features/room/ThreadBrowser.tsx
index ad55d0fdc..cb3cd904b 100644
--- a/src/app/features/room/ThreadBrowser.tsx
+++ b/src/app/features/room/ThreadBrowser.tsx
@@ -14,7 +14,7 @@ import {
   toRem,
 } from 'folds';
 import type { EventTimelineSet, MatrixEvent, Room, Thread } from '$types/matrix-sdk';
-import { MatrixEventEvent, NotificationCountType, RoomEvent, ThreadEvent } from '$types/matrix-sdk';
+import { EventType, NotificationCountType, RoomEvent, ThreadEvent } from '$types/matrix-sdk';
 import { useAtomValue } from 'jotai';
 import type { HTMLReactParserOptions } from 'html-react-parser';
 import type { Opts as LinkifyOpts } from 'linkifyjs';
@@ -26,6 +26,7 @@ import { nicknamesAtom } from '$state/nicknames';
 import { getMemberAvatarMxc, getMemberDisplayName, reactionOrEditEvent } from '$utils/room';
 import { getMxIdLocalPart, mxcUrlToHttp } from '$utils/matrix';
 import { UserAvatar } from '$components/user-avatar';
+import { MessageNotDecryptedContent, MessageBadEncryptedContent } from '$components/message';
 import {
   Chats,
   chipIcon,
@@ -241,6 +242,15 @@ function ThreadPreview({ room, thread, onClick, onJump }: ThreadPreviewProps) {
                 return <RedactedContent />;
               }
 
+              const type = rootEvent.getType();
+              if (type === (EventType.RoomMessageEncrypted as string)) {
+                return <MessageNotDecryptedContent />;
+              }
+
+              if (rootEvent.isDecryptionFailure()) {
+                return <MessageBadEncryptedContent />;
+              }
+
               return (
                 <RenderMessageContent
                   displayName={displayName}
@@ -316,19 +326,9 @@ export function ThreadBrowser({ room, onOpenThread, onClose, overlay }: ThreadBr
   // always be a no-op and left threadsReady=true prematurely.
   useEffect(() => {
     const onUpdate = () => forceUpdate((n) => n + 1);
-    const onDecrypted = (mEvent: MatrixEvent) => {
-      if (mEvent.getRoomId() !== room.roomId) return;
-      const relation = mEvent.getRelation();
-      const isThreadRelation = relation?.rel_type === 'm.thread';
-      const threadId = isThreadRelation ? relation.event_id : mEvent.getId();
-      if (threadId && room.getThread(threadId)) {
-        onUpdate();
-      }
-    };
     room.on(ThreadEvent.New, onUpdate);
     room.on(ThreadEvent.Update, onUpdate);
     room.on(ThreadEvent.NewReply, onUpdate);
-    mx.on(MatrixEventEvent.Decrypted, onDecrypted);
 
     let cancelled = false;
     const loadThreads = async () => {
@@ -391,7 +391,6 @@ export function ThreadBrowser({ room, onOpenThread, onClose, overlay }: ThreadBr
       room.off(ThreadEvent.New, onUpdate);
       room.off(ThreadEvent.Update, onUpdate);
       room.off(ThreadEvent.NewReply, onUpdate);
-      mx.off(MatrixEventEvent.Decrypted, onDecrypted);
     };
   }, [room, mx]);
 
diff --git a/src/app/features/room/ThreadDrawer.tsx b/src/app/features/room/ThreadDrawer.tsx
index e956c744c..5f680cce5 100644
--- a/src/app/features/room/ThreadDrawer.tsx
+++ b/src/app/features/room/ThreadDrawer.tsx
@@ -2,7 +2,7 @@ import type { MouseEventHandler } from 'react';
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import { Box, Header, IconButton, Scroll, Spinner, Text, config, toRem } from 'folds';
 import { Chats, composerIcon, X } from '$components/icons/phosphor';
-import type { IEvent, Room } from '$types/matrix-sdk';
+import type { IEvent, Room, CryptoBackend } from '$types/matrix-sdk';
 import {
   Direction,
   MatrixEvent,
@@ -390,32 +390,67 @@ export function ThreadDrawer({ room, threadRootId, onClose, overlay }: ThreadDra
         forceUpdate((n) => n + 1);
       }
     };
-    const onDecrypted = (mEvent: MatrixEvent) => {
+    const onRedaction = (mEvent: MatrixEvent) => {
+      // Redactions (removing reactions/messages) should also trigger updates
       if (isEventInThread(mEvent)) {
         forceUpdate((n) => n + 1);
       }
     };
-    const onRedaction = (mEvent: MatrixEvent) => {
-      // Redactions (removing reactions/messages) should also trigger updates
+    const onDecrypted = (mEvent: MatrixEvent) => {
       if (isEventInThread(mEvent)) {
+        const currThread = room.getThread(threadRootId);
+        if (currThread && !currThread.events.includes(mEvent)) {
+          currThread.addEvents([mEvent], false);
+        }
         forceUpdate((n) => n + 1);
       }
     };
     const onThreadUpdate = () => forceUpdate((n) => n + 1);
     mx.on(RoomEvent.Timeline, onTimeline);
-    mx.on(MatrixEventEvent.Decrypted, onDecrypted);
     room.on(RoomEvent.Redaction, onRedaction);
     room.on(ThreadEvent.Update, onThreadUpdate);
     room.on(ThreadEvent.NewReply, onThreadUpdate);
+    mx.on(MatrixEventEvent.Decrypted, onDecrypted);
     return () => {
       mx.off(RoomEvent.Timeline, onTimeline);
-      mx.off(MatrixEventEvent.Decrypted, onDecrypted);
       room.removeListener(RoomEvent.Redaction, onRedaction);
       room.removeListener(ThreadEvent.Update, onThreadUpdate);
       room.removeListener(ThreadEvent.NewReply, onThreadUpdate);
+      mx.removeListener(MatrixEventEvent.Decrypted, onDecrypted);
     };
   }, [mx, room, threadRootId]);
 
+  // Retry decryption for thread root events that failed because they were fetched before keys arrived
+  useEffect(() => {
+    if (!rootEvent?.isEncrypted() || !rootEvent.isDecryptionFailure()) return undefined;
+    const crypto = mx.getCrypto();
+    if (!crypto) return undefined;
+
+    const retryDecrypt = async () => {
+      try {
+        await rootEvent.attemptDecryption(crypto as CryptoBackend);
+        if (!rootEvent.isDecryptionFailure()) forceUpdate((n) => n + 1);
+      } catch {
+        // ignore
+      }
+    };
+
+    // Piggyback on other decryptions as a proxy signal for key arrival
+    const sentinels = room
+      .getLiveTimeline()
+      .getEvents()
+      .slice(-50)
+      .filter((e) => e.isEncrypted());
+    sentinels.forEach((e) => e.on(MatrixEventEvent.Decrypted, retryDecrypt));
+
+    // Attempt immediately in case keys arrived since the initial failure
+    retryDecrypt();
+
+    return () => {
+      sentinels.forEach((e) => e.off(MatrixEventEvent.Decrypted, retryDecrypt));
+    };
+  }, [rootEvent, room, mx]);
+
   // Mark thread as read when viewing it
   useEffect(() => {
     const markThreadAsRead = async () => {