I am getting exactly the same problem on Series X and cloud. My Xbox account is logged in (correct profile showing at the top right) but I get this message everytime i click Multiplayer. Have tried "quitting" the game from Xbox home to remove any quick resume problems....have tried reinstalling...all to no avail
Grounded 1 works fine ... just Grounded 2 is screwed for me at the moment. I have two very frustrated boys that cannot play together