Internal microphone not working

I'm running a ThinkPad T14s. There's been some recent additions to the
azalia driver to help make audio work a little better on this machine
(it now works and seems to get configured correctly).

However, I'm having problems getting my internal microphone to work.

I compiled my kernel with AZALIA_DEBUG (output attached), and it seems
as though the microphone is being picked up (also reflected in mixerctl
and audioctl). If I run something like Audacity to try and record audio,
it just flat-lines which makes me think it is attaching to the mic-jack,
not the internal microphone itself, but mixerctl doesn't seem to offer a
suggestion of what to change.

Audio recording is enabled in sysctl, and the device is configured as
accessible in the BIOS.

Any suggestions appreciated.