Monterey 12.1 external USB mic issues

Recently installed 12.1 and having issues with FaceTime recognizing my external mic (tried on both Shure MV5 and Rode NT-USB Mini). When connected, the mic shows input level in the Sound setting. Noticed in FaceTime/View, the external mic only shows up in Output, not Microphone. Having similar issues with Zoom not recognizing the default sound settings. In Zoom however, I've been able to manually toggle between the default and external mic to activate it. There are other threads here reporting the same issue. Also been working closely with Apple tier 2 support but nothing yet. So far have created a separate test user account, booted in safe mode, completely wiped my system and reinstalled 12.1 and many other attempted fixes. None have worked. Per another user, I plan on installing the earlier 12.0.1 on an external SSD to see if that works. Will update this thread with the results. BTW, I replicated exactly the same issues on my wife's M1 also recently updated to 12.1. This makes me think it's a widespread issue.