Having had sound problems with the later 5.0 releases I haven't bothered to update for a while.
Today I tried to load the latest image (5.1.004) only to find the infamous 'no sound' bug, I tried 2 flashes & system resets but to no avail.
I then flashed the previous version (5.1.003) & the sound is ok, so it looks like the buggy driver has crept back in to this latest release somehow.