Halo 2 Legendary not completed?

Games Halo: The Master Chief Collection
1

I beat all of the missions in Halo 2 on Legendary without skulls yet I do not have the achievement last I checked. Can this be fixed?

2

Play one of the levels over again on Legendary. Outskirts is the quickest.
Make sure that within MCC it shows you completed Legendary on every mission. If it doesn’t then replay whatever missions shows incomplete.