Did you click on “reset sounds” (or the nearest equivalent, can’t see menu screen on this device) in the ingame menu?
My troubleshooting went. …
Uh-oh, no sounds.
Check audio menu, notice the absence of an option for HD sounds (can’t recall if it was present before). Installed HD pack a long time ago, not deliberately refreshed since.
Steam to uncheck dlc for HD sounds and voices.
Retry, still no sounds in menu or in game.
Back to menu. Click “reset sound”, play with sliders. Sounds, both in menu and in game.
Steam to reselect HD audio dlcs.
The important bit for me was the fiddling in the menu and forcing a reset. I think this may have been all that was strictly required. I hope this helps, if not continue waiting for formal support assistance… but this is an easy thing to check and/or to overlook.