Master chief collection memory failure

Games Halo: The Master Chief Collection
1

I completed a mission on mc with another player
And after playing for HOURS we finally completed it once done the game automatically brought us to the next mission. He left causing the game to disconnect. So then I go to mc and try doing a mission but it says that I would lose my progress in the other one and thats how i found out it took away my 100%
Wtf

<mark>mod edit: moved to MCC Support</mark>

2

Which Halo game was this? What mission and what playlist?

3

> 2533274818084099;2:
> Which Halo game was this? What mission and what playlist?

It was halo ce truth and reconciliation legendary to the next level