That could not be the reason when I encountered the bug - I never use the queue.using queue mode caused dir size counting to stop working
Yesterday I encountered something similar (wrong action on a keypress in the file panel) - For a while pressing Enter on files resulted in the properties dialog to pup up - like if Alt+Enter had been pressed. I took TC x64 out of focus (using TC 32bit for a while in stead), and when I returned to TC x64, the Enter key worked alright again... Maybe related??