Figured I give this a shot even though the topic is months abandoned:
For who the hell knows what reason I can't get DLC packs to show up in the in-game menu. I bought the season pass ages ago when it was on sale but hadn't started playing through until now. Downloaded the Claptrap DLC but not any of the rest since at the time my 360 didn't have the HDD space. Now the DLC menu cycles between 1) not being able to pull up any DLC at all or 2) pulling up random selections of DLC, none of which include what I want (for example, right now I only see the compatibility pack and both halves of the Claptrap DLC, except the non season pass version of the first half of Claptrap). I've rebooted the game a dozen times, reinstalled it, and hardbooted the console. Nothing's working. I'm worried it might somehow be related to the season pass, and I would reinstall THAT, but the Xbox marketplace shows it as unpurchased despite it being installed and tied to my account...
Edit: not the season pass. Xbox.com does have it marked as purchased and lets me redownload, so I tried uninstalling and the DLC menu is still funky. Same with after.
Edit 2: Never mind, maybe? I see there's a general download/purchase server alert up for 360 games only. Maybe that's it? Doesn't really make much sense, but I guess we'll see...