WARNING, I'M WORRIED THIS MAY HAVE A CROSS-PROFILE ISSUE!
I have not unlocked this, after completing the achievement while my wife's profile, who had the achievement, was signed in.
Oddly, I have completed part of the
achievement before I started the campaign, as a similar impact from being logged in whilst another profile was playing.
We hit this issue logging in additional profiles for the
achievement, so until it's clear I'd suggest making sure you close the game / change profile before continuing (we changed profile at start screen, within the game, to be clear).