I posted this on the forum for the game but this is probably the best place to ask as I received no answer on there.

I've had some odd problems with some of the achievements.

Firstly I completed the game (story mode) on veteran, and the relevant achievement didn't pop. But then I played it through on elite and instead of the elite achievement popping, I got the previous one for doing it on veteran.

I looked around and there are quite a few other people with the same problem but none have come on here to report it.

Is this the first you have heard of this glitch, or are you working on it? Really disappointed that I didn't get it after all that effort.