This is in Halo MCC on PC. I’ve been playing through the Halo CE LASO with a friend and he is the one that has been the host. We completed the final mission last night and the achievement popped for him for completing the Halo CE LASO, but not for me. We previously went through Halo Reach LASO in the same configuration and didn’t have a problem with it. I did get the achievement for completing the last mission though.
I checked the progress on my own LASO playlist and it says 7/10 and looking at the mission list, all of the missions have a blue highlighted bar except for the first 3 missions. And when I resume the playlist it puts me in the first mission. Any ideas on the best way to resolve this? I did complete all of those missions in co-op as part of the playlist already.