I've had this bug intermittantly and it drives me crazy. You open log and transfer like before, but this time you can't hear the audio, so you can't log and transfer sound bites. Restarting sometimes helps, but not always. And no, it isn't a Easy Setup issue or Audio/Video settings.
I don't know if it is a fix, but today restarting FCP or the Mac didn't help. Refreshing AV devices under the view menu did (alt-f12), however. Your mileage may vary, but give it a try when rubbing the lucky rabbit's foot doesn't.