Achievenent glitch

I have done all the campain on leggendary, And i didnt unlock yet the achievement.
On Halo waypoint i have already done all the mission And on halo 5 too, but the achievement still not unlock.
what i have to do to unlock the achievement?

> 2535430117558642;1:
> I have done all the campain on leggendary, And i didnt unlock yet the achievement.
> On Halo waypoint i have already done all the mission And on halo 5 too, but the achievement still not unlock.
> what i have to do to unlock the achievement?

Were you online when you played all the missions?

Sometimes you can fix such glitches by removing your profile from your console - this forces all the data to resync from the server then signing in again and then completing another mission (suggest Meridian Station).