I have ran through the game multiple times, alone and in co-op, yet it tells me I have 27/30 Cog Tags when I have in fact gotten them all. Yes, I have earned them all because I ran through the game and none of them were there anymore.
Also, I have the strategy guide for getting them so know where they all are, yet it still tells me I don't have them all. But I have.
Is there some glitch with this because some of them were obtained in a Co-Op game? How do I fix this?