I wish I could say this was fixed but it happened to me again, and I had to go a full stream with a non-talking avatar.
It's possible it was something on my end because Linux audio is hell.
The terminal was showing me errors over Pulse Audio not being in a valid state (yet everything else that wanted access to the mic worked just fine).
And then the next day, it worked again.
So, nothing really for me to go on and no useful info to share unless the kaiakairos can point me to where log files can be found.