Ran into a similar issue. I found my microphone worked depending on the angle of the screen. Clearly seemed to be an issue with the cable at the lid joint. Same behavior in Windows or Linux. Lots of testing with support and they came to the same conclusion.
Unfortunately, the laptop is 2 years old and out of warranty.
What’s worse is that the cable is not available for purchase.
So I had to buy a whole new lid. What a waste! $100 after tax and shipping for a $5 cable. Definitely not the Framework experience I was expecting when I bought it.
sigh
Brian