WHY cant i sign in a guest account

i have sign in with xbox button load up gears and i cant see my guest acoount??

then press start on secound pad sign in and it does nothing

i know there is spilt screen i did the story a while back

When on the main menu click “LT” and have the second controller on. It will then show “player 2 press start” and it will say add guest.

ok it does say that i press start it doesnt sign in im not sure why

My buddy is having the exact problem on his series x. We’ve played hundreds of hours on our own accounts with two controllers on separate consoles. We have even gone as far as to do split screen boosting for some versuses achievements. All of a sudden he cant connect a second controller with a guest or another account. His controllers are up to date and any other games worked just fine. Weird