Apparently if the game is 1.6g in size when you check your hard drive then you've got the broken version of the game, which will lock you out of the DX DLC achievements. Supposedly in December of 2011 there was another version of the game released, which fixed this problem. This version of the game was 1.50g in size and it is the working version of the game that allowed you to unlock the DX DLC achievements.
I recently bought the game and when I went to download it, it said it was 1.50g in size, but when I checked my storage it was 1.6g in size. This means the buggy version of the game is somehow back up available for purchase, which it shouldn't be. I keep checking every week to see if the correct version is available for download, but it is always the 1.6g version once it downloads. So, apparently if you check your storage and see 1.6g then you have no chance of unlocking the DX DLC achievements.
Kinda sucks they fucked up and put the buggy version of the game back up for download. I purchased both the game and DX DLC and normally I don't give a shit about glitched achievements because I have so many of them on my card already. But, because they did release a working game at one point (in 2011), I'm hoping the fixed version of the game somehow makes it back into the marketplace for download. From what I understand from the thread I observed on 360.org, if your file size says 1.6g then you won't be able to unlock DX DLC achievements, until the 1.5g version is back.
If anybody has any info relating to this (info such as you have the 1.6g version, but still unlocked the DX DLC achievements) then let me know. Thanks
Here is the threads relating to the issue:
http://www.xbox360achievements.org/forum/showthread.php?t=37...http://www.xbox360achievements.org/forum/showthread.php?t=30..."I've seen enough horror movies to know any weirdo wearing a mask is never friendly"