Achievement unlocked but showing 11/12 instead of 12/12 for achievements completed

An hour ago I got the achievement for beating the game on normal for the game Deadly Premonition on XBox 360. My gamerscore was updated correctly but when looking at my achievement overview it shows that I have 11/12 of the achievements for the game instead
of 12/12 and 850 gamerscore for the game instead of 1000 gamerscore. I tried getting another achievement in a different game and that registered just fine but the 150 point achievement in Deadly Premonition still didn't correct itself. I checked my stats on
xbox.com and that also shows that I have the achievement but incorrectly displays 11/12 and 850 instead of the correct 12/12 and 1000 just like on my XBox 360. How can I fix this or will this just fix itself over time?

:)

 

Completed game does not appear completed - UPDATE

I unlocked the last achievement on Gotham City Impostors (Prestigious - accept your first promotion for 25G)

The game doesn`t appear on my completed games and in xbox guide>games & apps> achievements it shows 11 of 12 achievements unlocked for 175 gamerscore, but when I click on the game it shows all 12 achievements unlocked and this last one even counted for my
gamerscore.

I cleared the cache, deleted my profile and downloaded it again, got another achievement and nothing worked.

A friend of mine had the same problem with the last achievement of Hitman Absolution over a year ago and it still doesn`t appear as a completed game.

PS: My friends when comparing games with me see 11 of 12 achievements and when they click on the game they see all 12 achievements unlocked, so the problem probably isn´t the achievement.

PLEASE HELP!

 

Enforcement Team - Completed Game does not appear completed

I unlocked the last achievement on Gotham City Impostors (Prestigious - accept your first promotion for 25G)

The game doesn`t appear on my completed games and in xbox guide>games & apps> achievements it shows 11 of 12 achievements unlocked for 175 gamerscore, but when I click on the game it shows all 12 achievements unlocked and this last one even counted
for my gamerscore.

I cleared the cache, deleted my profile and downloaded it again, got another achievement and nothing worked.

A friend of mine had the same problem with the last achievement of Hitman Absolution over a year ago and it still doesn`t appear as a completed game.

PS: My friends when comparing games with me see 11 of 12 achievements and when they click on the game they see all 12 achievements unlocked, so the problem probably isn´t the achievement.

PLEASE HELP!