diff --git a/src/renderer/components/team/activity/ActivityTimeline.tsx b/src/renderer/components/team/activity/ActivityTimeline.tsx
index 00dde0b1..137cb808 100644
--- a/src/renderer/components/team/activity/ActivityTimeline.tsx
+++ b/src/renderer/components/team/activity/ActivityTimeline.tsx
@@ -44,11 +44,8 @@ const MessageRowWithObserver = ({
 
   useEffect(() => {
     messageRef.current = message;
-  }, [message]);
-
-  useEffect(() => {
     onVisibleRef.current = onVisible;
-  }, [onVisible]);
+  }, [message, onVisible]);
 
   useEffect(() => {
     if (!onVisible) return;
diff --git a/src/renderer/hooks/useTeamMessagesRead.ts b/src/renderer/hooks/useTeamMessagesRead.ts
index dd14df40..d9145514 100644
--- a/src/renderer/hooks/useTeamMessagesRead.ts
+++ b/src/renderer/hooks/useTeamMessagesRead.ts
@@ -27,5 +27,6 @@ export function useTeamMessagesRead(teamName: string): {
     [teamName]
   );
 
-  return { readSet, markRead };
+  const effectiveReadSet = !teamName ? new Set<string>() : readSet;
+  return { readSet: effectiveReadSet, markRead };
 }