I'm playing on a PC with an Xbox Game Pass account and can't play multiplayer; it asks me to sign in with an Xbox network account and have an internet connection. Of course, I have an Xbox Game Pass account and an internet connection. I've reinstalled the Xbox Game Pass app and Grounded 2, and cleared the caches, but the same message keeps appearing. This happens on any computer I try to log in to with my Game Pass account.
The problem started when I tried to play while my son was signed into my Xbox Game Pass account on another computer, because he was playing another game from my library.