Halo defiant/noble, default map packs will not show on the Halo CEA disc, it will only appear on the Halo Reach disc. Not really why 343i did that but thats how it is at moment because the CEA is not the full edition of Reach since its CEA multiplayer only.
Apparently, there used to be some glitch where there was a cap on the amount of DLC you could have in Reach, and the pre-order armor permutations contributed to it. Basically, you have too much DLC. There’s a publicly-known fix that doesn’t require you to delete or lose anything, but I don’t know where it is.