I have the same issue with my librem 13 v2.
I use Qubes OS and thought it was due to some configurations mistakes. But when I switch to PureOS, it goes on to flicker and no mic is detected.
Moreover no mic is detected when I plug a jack microphone.
$ cat /proc/asound/cards
0 [PCH]: HDA-Intel - HDA-Intel PCH
HDA Intel PCH at 0xd152c000 irq 306
$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC269VC Analog [ALC269VC Analog]
Subdevice #0: subdevice #0
But I can’t record any sound from this device.
Please, do you have any idea how to fix this ?