I beat the Halo 5 campaign a while back on legendary solo. I just realized today that I did not receive the achivement for it. When you look at my service record in game or here in the waypoint site it says I completed solo on legendary for all 15 levels. How do I get my achivement?
Are there any individual mission achievements that didn’t unlock whilst you did it as well? If so, the mission(s) did not register properly on the server side, and you’ll have to keep replaying them until their achievement(s) show, and then your overall achievement should unlock.
I already had all the mission achievements from a previous run through so that isn’t an option. I saw my progress toward the achievement is 93% so I’m only missing one mission, I just don’t know which 
Ah, that’s a pain. Can you think of any missions where you were disconnected from Xbox Live or had to leave and come back to them? They’ll probably be the most likely ones.
The halo campain on legenadary was unbeatable, i was stuck on the mission glassed where u fight the mighty warden, there were three. Ive still havent completed
MiniRoboRoyal - I remember that fight. It is possible but I agree it seems nearly impossible. I have been able to sucessfully take out all 3 wardens twice legitimately. But there are ways to skip that fight if you want.