Hi, Teams on Mac OS Big Sur seems to be confusing the Mic and Speakers sometimes, now this usually works fine - but sometimes it reverts back and Teams will have no sound output, and will sometimes crash or freeze completely:

Any idea what is happening or how I can fix it? I've tried reinstalling Teams several times, and this is persistent across user accounts. I'm using a USB sound card, and a Dell D6000 Thunderbolt Dock.
Any help would be much appreciated! Cheers.