Resolve "(File Drop Mode) : File sent from the user in file drop mode is not received by another user"

src/components/chatMixin.js

@@ -154,7 +154,7 @@ export default {
 
         case "m.room.message":
           if (event.getSender() != this.$matrix.currentUserId) {
-              if (event.isThreadRoot) {
+              if (event.isThreadRoot || event.isThread) {
                 // Incoming thread, e.g. a file drop!
                 return MessageIncomingThread;
               }