This is just a guess but is it possible that you have something plugged into the audio connector like wired headphones that don't have microphone support? I think I read somewhere that the audio connector supports an external microphone and if this isn't supported by your headphones it might short out the internal microphone.
A voxel is a three dimensional pixel! Murray Foster
That's quite a design flaw if true. I was using external headphone when my mic but the bullet a few days ago. Some social apps auto mute you if you don't use headphones such as Altspace, which I use. I've also read you don't need headphones with the Go as it doesn't interfere/ghost.
you have to give permission for the app to use Mic, for that ->go to settings and switch on the microphone option ->then go to device->permission and select the app then grant access to microphone option.(for example: youtube). its worked for me.