Halo 2 Completion Achievements Not Working

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I have completed the Halo 2 campaign 4 times since 2016 and only the completion achievement for Cairo Station has ever populated. I have tried all of the suggestions I could find on both the Microsoft and Halo Waypoint forums and nothing is working. Even tried calling Xbox support but they said it’s a dev issue. I am trying to complete the Legend achievement so that I can access the Helioskrill armor set on Halo 5 but if this isn’t fixed, it’ll be impossible. I really need this resolved.
My gamertag is thatguy32198. The last time a completion achievement for Halo 2 populated after completing the relevant prerequisites was in 2016 and it was for completing Cairo Station. None of the others are reflecting as completed on the achievements but they are on the level selection screen. I have completed it twice this year both on solo and coop. I have always been the Host of the games and have always been connected to xbox live. All other completion achievements are working on the other games currently. It’s just Halo 2 I am having problems with. Thank you for you assistance.
-Guy