Having issues with invites on Xbox 1.
Any invites result in being told that the session is reinitiating, 1, 2, 3, then a black screen.
After that I'm told the servers are under maintenance & I have to force quit the game.
It's the same either end. If I send the invite, the other player runs into the problems, If I accept, I get the problems.
There' nothing wrong with either internet connection, or multiplayer connection & NAT is open on both ends.
If we search for a game individually, the game is fine & we can play, but not together as our levels & MMR are different, therefore the servers are fine.
Incidentally, there are no problems of this kind on PS4 as someone else in the house is currently teamed with their friends, so it's just Xbox 1