Halo 3 Big Team Multiplayer Lobbies MCC

Loading into a big team battle with a buddy of mine and our lobby was split

4 of blue team (my team) were in my game with 7 Red team players
He loaded into a game with 3 Blue team and 1 red team player.

This hasn’t happened to us before and we have been killing MP for the last 2 weeks pretty much straight, anyone else had this issue?