Granted, this isn't a true solution, but it is an acceptable workaround for now. I now just set both games to 'full screen borderless window' mode and I get the same full screen visual without the sound failure.
Turns out that, for whatever reason, having the game switch to full screen mode caused the audio to stop working for that game. I set Kholat to windowed mode so that I could monitor something while the game was active and the sound finally started working. Boju, I tried uninstalling audio devices and reinstalling but that didn't seem to solve the problem.
