diff --git a/lib/reducers/master-reducer.js b/lib/reducers/master-reducer.js
--- a/lib/reducers/master-reducer.js
+++ b/lib/reducers/master-reducer.js
@@ -188,7 +188,11 @@
   );
 
   const { threadActivityStore, threadActivityStoreOperations } =
-    reduceThreadActivity(state.threadActivityStore, action);
+    reduceThreadActivity(
+      state.threadActivityStore,
+      action,
+      onStateDifferenceForStaff,
+    );
 
   const { store: queuedDMOperations, operations: dmOperationStoreOperations } =
     reduceDMOperationsQueue(state.queuedDMOperations, action);