This tends to start happening after I alt-tab and return to the game, and doesn't stop untill I restart the game. I have hybrid controls enabled (allowing both keyboard+mouse and controller). If I move the mouse, all sound from the game completely stop. If I then give any input on the controller, the sound starts again.
Edit: actually it just starts happening after the game has been running for a few minutes.
Windows 10 Education 64-bit 20H2 19042.1466. AMD Ryzen 7 5800X CPU. 64 GiB RAM. Nvidia GeForce RTX 2080 Ti