So my friend just started playing D2 on a Windows computer, and I'm on an Xbox One X, and we were trying to do the campaign together, but it won't let me join him. When I let a mutual friend of ours who also plays D2 use his account to friend him in game and join him, it gave the same message: "player can only join cross play disabled fireteams" and yet when we disabled it, it still wouldn't let us join him. According to him, he doesn't have an option to turn it on or off, and when I use /join, it says "player does not have cross play enabled" or something of the sort. How do I fix this, and does it matter that he is only Guardian Rank 3 while I'm at 7?