Any idea why in Mail 7.0 (part of OS X 10.9 Mavericks,) when I select a group of messages in the Sent Mail folder and do Message --> Apply Rules command, nothing happens?

(In prior versions of OS X back to 10.5, my extensive list of 70+ rules automatically moved messages from my Sent folder to various other sorted folders. I have several plain POP3 accounts set up in Mail.app, not leaving messages on the server.)