Completed a flawless run on Crota this weekend and the achievement didn't show up. Everyone in my fire team got on, but I did not.
In case the link doesn't work, here is the game;
https://www.bungie.net/en/Legend/PGCR?instanceId=5406286643&characterId=2305843009294408346
I have a new Xbox One S Console, all info is saved on a portable drive.
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I think you can try to sign out of your profile, then sign back in. Then load the game back up again. I know I had to do that, when I fully leveled a subclass on my Hunter, to be able to get that Achievement.