This is probably a very specific bug that probably no one else experiences.
Description: Sound won't play through the only available playback source.
How or when it occurs: When I turn sound on, the client decides to play audio through a disabled device, and not my active/default sound device. It can only be temporarily fixed by enabling the disabled device that the client is somehow using and then re-disabling it, forcing it to use the default audio. However, after a non-specific amount of time (and seemingly no game sounds), the client switches back to the disabled device.
More info: My current audio device is a FiiO K7 DAC using USB, outputting to Sennheiser HD 660 S. All other applications and games have no similar issue.
Screenshots/Video: https://youtu.be/hgqRER_uBdc
Edit: Have potentially resolved this by unchecking "Allow applications to take exclusive control of this device" in advanced properties.