Topic: 2 controllers when activated doesnt respond ingame

Hey all, I recently bought xbox series S. Configured 2 wireless controllers.
They work individually for all games.
I turned on Co pilot as well. But when I turn ON copilot. both controllers are able to take input for navigating xbox console menu (going to settings, choosing game etc). but as soon as the game starts none of the controllers buttons responds (they are ON but no button press seems to work)
at this point if i turn OFF any one of the controller, the other controller i am able to use successfully to play game. or if I turn off co pilot it starts working again.

All of these trouble i am facing because i wanted to setup local coop /guest user to use 2 controllers for playing games with 2 players.

Not sure why that is happening. I don't play 2p very Often but the other day a buddy was at my place and we played windjammers without any issues

@Beagle

I am actually looking to play split screen games. not controlling the same character in a game. but before i could proceed to check any split screen games everytime i try to prepare the devices this keeps happening.
so if i understand you correctly, for split screen games i dont need to turn ON co pilot? all i need to do is log in to any games that works with split screen with both controllers turned ON?