Local multiplayer does not work (Xbox Series X)

[IronKaizer1]

In Super Mega Baseball 3 I could easily add a 2nd local player just by pressing "A" when choosing the teams. In Super Mega Baseball 4 this doesn´t work. Every time I press A on the 2nd controller I can only remain with my main account (and just switch to the 2nd controller but as a single player and the 1st controller is deactivated, then) or I am asked to choose another account.

I have already tried to add manually a guest account but there is no change. I also have plugged in the 2nd controller after starting the game in order to give the system a "kick" - no result.

I have the game fully installed (no cloud gaming).

I really do not have a clue what is going on. There are a few other posts in the internet describing exactly the same problem but with no solution in the answers.