Specific headset does not work with specific controller. Help?

The hard reset didn't work, again, I'm afraid.

I've tried plugging the controller in, but I tried replacing the batteries earlier, and this doesn't appear to have made any difference. I'm not sure what you mean about using USB for the headset? Or do you mean plug in the controller and then the headset
into the controller (I've tried this anyway, in case it is what you mean).

I unplugged and replugged from the home screen, but still no luck. Checking firmware again lists as up-to-date "No updates needed. Your controller is already up to date" (3.1.1221.0).

Still no detection of the headset.

No problem, I don't believe its your headset at this point. It sounds more like the controller having the issue with recognizing the attached headset since you confirmed the older controller does indeed work just fine with this headset.

A few things you can try with the controller that is giving you issues.

• The auto-detect feature of this update may not work immediately if you plugged your stereo headset adapter into the controller while downloading a system update, or while the console was turned off. To resolve this, go to the Home screen and unplug the
  adapter. Then, re-plug the adapter into the controller.
• You only need to update your controller one time to use the stereo headset adapter. However, if you plan to use the stereo headset adapter with other Xbox One controllers, you’ll need to follow this process for each controller. Additionally, check for new
  updates periodically as Xbox frequently ships new controller features and improvements.
• If you try to update a controller that was already updated, the system will check the controller and proceed to the success screen within a few seconds to indicate that it’s already updated.

That way we can rule out trying to re-update the controller without the headset plugged in. Then update the controller, and after its complete, try to the headset again.

Yeah, the volume control is under the right earcup and is on max. The mic mute is operated by pushing back past a click. Both are operating fine with the older controller.

Thanks for putting the time in haha, hopefully we can sort this out!

And both are on the latest firmware, I checked both today.

I ran through the checking for updates 3 times and was told that the controller was up to date each time. This was run from Devices and Accessories. I'm not sure where else I would be checking/running this from?