Hi all, I've just finished doing some maintenance on a few of our systems (we use them for digital signage) and noticed that all the ones I've touched today have lost audio.
After some digging I found that the issue is Pulse Audio being installed via some package dependency; apparently on the Rpi Pulse conflicts with Alsa and audio stops working when they're both installed. Not 100% sure what package pulled in Pulse (kinda putting out fires trying to revert changes at the moment), but I'll look into it later.
Just as a general FYI to anyone having random audio issues with an Rpi 2/3, check if Pulse is installed. Removing it and rebooting should fix the issue.
Cheers, HDZ