This happened around a year ago so apologies if this has been fixed. Friend and I were going through Halo 2 on legendary co-op to complete the playlists. After the enforcer sentinel fight before the gandala my friend and I de-synced for lack of better words. We would still be in each other’s game, but we would be walking differently in each other’s game. I was walking into a wall for him and he was continuously walking off the map for me. But we weren’t doing these things in our own games. I tried reverting the checkpoint multiple times and we eventually died enough for the mechanic of reverting us back 2 check points. It’s was just fine until after the gandala then we de synced again. We were recently talking about trying it again so I want to make sure it won’t happen again. Thanks for any tips and such.
A lot of things have been fixed over the last year as MCC has been throuh some significant updates. I’m fairly confident that the desync issues were fixed in those updates