Co-op desynchronized

A friend and I were attempting to finish halo 2 on legendary however halfway through the mission our game appears to desynchronize and we end up in 2 different instances of our game. The problem arises as halo 2 legendary had iron skull defaulted to on, further complicating things as I can see when he dies or kills my now idle character in his game through point deductions however we can no longer progress through the missions. Any assistance would be greatly appreciated.

Both of us are on an open nat showing no Xbox live issues.

My friend and I are currently having this exact same issue and we both are researching how to fix it. Sounds like a bug that 343 has not patched yet. A lot of people are reporting this issue. Let me know please what you find out if anything.

Will do. I was hoping a fix had been posted but alas, no luck.

Do mods not come in here to let us know what’s going on with these issues?