Completed Halo 3 Laso playlist and it didn't count

I recently completed the Halo 3 Laso playlist with 3 other people. The Halo 3 Laso nameplate and Halo 3 playlist completion counted for the host, but not for the rest of us. We checked the playlist and it said we didn’t complete “arrival,” the 3 of us watched “arrival,” got 11/11 complete, but still don’t have the nameplate or the achievement.

> 2533274863579645;1:
> I recently completed the Halo 3 Laso playlist with 3 other people. The Halo 3 Laso nameplate and Halo 3 playlist completion counted for the host, but not for the rest of us. We checked the playlist and it said we didn’t complete “arrival,” the 3 of us watched “arrival,” got 11/11 complete, but still don’t have the nameplate or the achievement.

Try hard resetting your console. That normally works.