I got two Xbox One controllers with the windows dongle, working fine, except only user #1 can toggle the RetroArch menu. I changed it to L3+R3 and switched which controller is #1 to test it out, too.
Is there any way to let any of the controllers toggle the menu?
Otherwise, I gotta use my wife’s controller to play solo and switch between games. 
I believe this is normal, unfortunately. There’s an option to allow all players to control the menu, but I think only P1 can open it.
Why is it normal? Sounds like a strange lock on an option that might as well be open to all controllers.
It’s not intentional but it’s also not easy to fix (apparently; I don’t know much about that particular issue, but I remember when bparker(?) was working on it and he said as much).
That’s a shame. Thanks for the info. I’ll look to submitting a bug report / request then.