Hello dbpy,
It seems to be similar to what was reported for Corebook X
Micro doesn`t work - Laptops / CoreBook X - CHUWI | Official Forum
Can you confirm you have the small holes for mic and check audio settings and device manager?
It may be either a driver issue or setup.
Also, go to settings, Privacy. Usually for ZOOM and other chat apps, due to privacy settings, apps are not allowed to use it.
You may do a quick test as well and open Sound Recorder to check if it capture some sound.
Regards