Having recently just downloaded the DLC thanks to bs angel’s last code dump, I did come across the same “Content not showing” error that many people have been hindered with. However resolving the issue is no where near as complicated as it would seem. For those with the DLC, in the main menu press Y to bring up the network mode tab. From there simply change your network to My Xbox 360 Console and you’ll now be able to peruse the maps without needing to clear cache’s or delete earlier content.
Please note however that doing this stops you from being able to access multiplayer, but to do so again simply change your network back to it’s prior setting.
If anyone has a difinitive fix that makes the maps show up in both local and online play, please post it here and I’ll add it to this post.
Edit: Well whatdya know, after going back from local to network the maps show up fine in both modes. There’s our fix people.