Achievement is not given in the game

Hi Lagolaz! Sorry to hear about what happened. Let's do our best here to get this sorted out.

To isolate the issue, is this the only game you're having an achievement issue? How about other games?
Have you waited up to 72 hours upon the completion of your game achievement for it to be completely synced through the Xbox network?

I suggest that you try all the recommended troubleshooting steps found on the official thread link below about achievement issues.
https://answers.microsoft.com/en-us/xbox/forum/...

If you tried everything and still having the same issue, you may need to file a bug to Team Xbox for further investigation. The complete guide is on the thread above.

Have him look under his commendations and ensure that every level has the box for the commendation filled. The level (or levels) that aren't checked will have to be completed again.

-

It's under player commendations.

Go into campaign mode and scroll through each mission on the select screen. It will show you which ones have been completed (for co-op and single player) and what difficulty. Probably skipped the prolgue like Bob said or one of the levels didn't read for
some reason.

Mine is sequence 3. It isn't unlocking and I beat the game

Yes, nice one, had a flick through them, and sure enough one chapter with no rank against it, played it through and up they popped. Happy days.