diff --git a/lib/components/chat-mention-provider.react.js b/lib/components/chat-mention-provider.react.js
--- a/lib/components/chat-mention-provider.react.js
+++ b/lib/components/chat-mention-provider.react.js
@@ -71,7 +71,10 @@
   );
 }
 
-function getChatMentionCandidates(resolvedThreadInfos: ChatMentionCandidates): {
+function getChatMentionCandidates(
+  threadInfos: { +[id: string]: ThreadInfo },
+  resolvedThreadInfos: ChatMentionCandidates,
+): {
   chatMentionCandidatesObj: ChatMentionCandidatesObj,
   communityThreadIDForGenesisThreads: { +[id: string]: string },
 } {
@@ -200,8 +203,8 @@
   );
   const { chatMentionCandidatesObj, communityThreadIDForGenesisThreads } =
     React.useMemo(
-      () => getChatMentionCandidates(resolvedThreadInfos),
-      [resolvedThreadInfos],
+      () => getChatMentionCandidates(threadInfos, resolvedThreadInfos),
+      [threadInfos, resolvedThreadInfos],
     );
   return {
     chatMentionCandidatesObj,