Xbox accessories app.

You can remap by using the accessories app https://support.xbox.com/en-US/xbox-one/accessories/customize-standard-controller-with-accessories-app

Check this link for a possible solution:
https://support.xbox.com/xbox-one/accessories/customize-standard-controller-with-accessories-app

You can try installing it again or clearing the MAC address/power cycling the console to refresh it. I would also just check to make sure it doesn't need an update

If the power cycle suggested above doesn't work:

Are you doing this on Xbox or Windows 10? (There's an Xbox Accessories app on both platforms.)

If the one you're trying isn't working, you can attempt to use the app on the other platform (if you have it available) to see if that is any better. Changes made to the controller settings in the Windows 10 app would still, I believe, hold true when you use
the controller on Xbox One.

If you talked to an actual Xbox Support Agent saying that, they probably use a Nintendo or PS. But If you're in one of the Xbox Insiders Preview rings like the Alpha Skip Ahead ring, that might be why it won't work. It works fine on my console and I'm
in the Delta ring now but going back to the Public OS version soon. I wish you luck though.