I will dig up and post my system specs too in a few mins but I just wanted to get this posted in case anyone has encountered this and have a fix. I dont think this is a game problem, steam problem, or playback device problem. Tales from the boarderlands and vermintide I just installed and neither are playing audio. Bloodbowl I had used to play with audio, uninstalled it, months later reinstalled and played with audio working fine, but then it stopped too. Hearthstone and diablo used to play audio then they stopped (likely some windows update borked it). I dont know if I should bother reinstalling any games because I dont think that will do anything. I even tried them while they were both unchecked too. I tried going into the advanced properties for my playback device to make sure the Exclusive mode boxes were checked as they should be. I have found new video drivers were available so I uninstalled video drivers, restarted, and installed the newer video drivers.

I have uninstalled audio drivers, restarted, and reinstalled audio drivers. I have verified the intergrity of the cache for each of the games. I have checked for windows updates (some updates installed but none were relevant to this and none fixed it). I have tried disconnecting my second display just to check and that did nothing. I have made sure that all other Playback devices are disabled so the monitor is the only possible playback device. I have also disabled all Recording deviced and unplugged any recording devices. The same applications do not appear in the audio mixer. I tried bypassing my monitor and plugging the aux directly to the motherboard but that was clearly never going to work.

I have no audio card but run an hdmi cable from my video card to my monitor (and an aux from my monitor to my speakers so i can change to ps4 and use the same speakers). Several games (Vermintide, bloodbowl 2, tales from the boarderlands, hearthstone and diablo) are not playing any audio and not appearing in my audio mixer.

This isn't exclusive to my steam games and has also happened to hearthstone, & diablo 3, but not overwatch.

Volume mixer not opening windows 10