Halo 3 ODST Achievement Help.

So While Halfway through Halo 3 ODST Expansion for MCC My game reset its save from mission 5 to mission 2, So I went and started a new game from the last mission I did on legendary. When I completed all missions on Legendary I did not get any achievement. Anybody have help?

alot of people are having issues with achievements not unlocking just give them time they will sort it out soon

So ya think i’ll have to redo It again?

no they will give everyone a patch update and it will unlock once you sign back onto the game i hope but you got to wait for the patch

Anybody need help with this?