Lumia 920 on AT&T, and since the Black update (I'm pretty sure) the "intermittent loss of volume control" bug is driving me crazy: I'm listening to a podcast (Podcast Lounge) and realize at some point that turning the volume up/down isn't doing anything. The numbers go up and down but the sound level does not change. Pausing or re-starting the podcast doesn't do anything. Quitting and re-starting the app doesn't do anything. If I go into my on-device music collection and play a track, the volume controls suddenly work. When I return to Podcast Lounge it plays at the new volume, but the volume controls still do not work (usually). Sometimes I'll turn the phone off/on and I think that usually works. Most times I've just moved on to something that I need to get done and I forget about it until it happens again. I guess this is not just an issue for Podcast Lounge.
I've noticed two other frequent issues, and these may in fact be Podcast Lounge problems-1)I'll pause from the headset button then click the headset again in a few minutes to resume, only to realize that the podcast has stopped playing and is no longer accessible through the lock-screen controls. 2) The headset control for pause/play will randomly stop working and I'll need to use the lock-screen controls.
Fortunately I have not experienced any bugs related to phone call or microphone audio. I saw someone above mention "flip to silence" and I did have that enabled. I'm going to disable that, though I'm guessing that will not have any impact.