Midnight completion still not unlocking

Games Halo: The Master Chief Collection
1

I first beat this level back in June 2017, and at the time didn’t get the achievement (and therefore none of the game completion achievements). I’ve beaten it a couple times since then with no more luck. With the latest update just out, I just tried playing through it again, but still, no unlock. No score or time shows on my Service Record.

This is all in vanilla Legendary, no skulls.

2

Do not know if there is ever going to be a fix about it.
That’s a shame, but I’m quite sure it is a long date problem, so it would be really hard to fix

3

For what it’s worth, it finally unlocked when I played it on Easy… trying again on Legendary now to see if I can get all the other completion achievements.