I just played through all 5 chapters of spartan ops chapter 9, Key. I played all 5 missions, and the achievement tracker only shows 4 out of 5 complete. I am running solo legendary so this is a pain in the -Yoink-.
Since Season 7 dropped none of the badges are showing to indicate that I’ve actually completed them, but I did all 5 chapters and for some reason 1 is registering as not complete, and I have no way of knowing which one it didn’t accept without replaying all 5 chapters again.