Hey guys, after 3 days of stressing and trying everything, I finally found a solution to the DLC not appearing in game.
I have only been able to test this with a physical copy of Halo 3.
- First thing you want to do is uninstall Halo 3 and all map packs.
- -Next, create a new Xbox Live Account with a new email address. (Anything will do, it’s only needed to download the map packs) - -Once you have created the new account, install the Halo 3 disc and launch
- -Once in the menu, press start and go to marketplace
- -Select the first map pack, select download. (It will then say "You must go to Manage Game to install)
- -Go to Manage Game, and go to Ready to Install, it should appear there (If it doesn’t, search and download it manually from the store)
- -Let the map pack install, then go back to Halo 3, to make sure it appears in Custom Games -Do the same for each map pack, step by step. (Download and install one, then go back to Halo 3 to check it has appeared in Custom Games.
- -Once they have installed, and they are appearing in Custom Games, quit Halo 3, sign out and sign back in with your original Gamertag
- -Boot up Halo 3 again, and all of the maps should appear!