MMDevice not working anymore due to bogus audio device
Related to #26996 (closed)
Sometimes it seems MMDevice can get into a weird state where it ha a invalid audio device saved into the preferences and then no longer functions properly, and in this state even changing the audio device in the Qt interface did not have any effect (and Qt still showed the Device as "default" even though apparently thats wrong) or fix the issue, for me, with 3.x at least.
This should be investigated further. Right now the only solution if in this state is to reset preferences (or for the user to manually remove the device in the advanced prefs or from the config file).