My Xbox One has muted itself so I can hear others but can't talk with them

I have had this happen to me & my friends. Did he try leaving the party and starting a new one? Also, possibly restarting his Xbox? The time that it has happened to me, it fixed itself in a few minutes. Unless he changed a setting, more than likely it
is not a problem on his end.

Have you tried the steps in this support, Update xbox wireless controller?

If you use multiple controllers, they all need to be updated.

I prefer the USB method.

Yeah, I'm pretty sure it's not a headset issue. I replaced my M80 mixamp (Astro) with a brand new one and nothing changed. The headset itself can't mute others, only the console has the ability to do that, and there's no way to tell the headset to tell
the console to mute the party. It has to be an issue with the xbox itself.

I can hear audio. It's just chat I can't hear. So if I'm in a lobby it's like I have everyone muted. As soon as I pull the chord from the adapter I hear others talking. They can hear me through Kinect

I think you missed this part:

In EVERY GAME and in party of the dashboard I also have a mute icon next to my gamer tag. I CAN HEAR AND TALK TO OTHERS in "Party Talk" or in "Game Talk" and they can hear and talk to me too.

I got three controller at home and I've tried them all!