Okay so this just happened to me as i went to the Brotherhood of steel hideout shack near the boomer faction camp as soon as i went into the cabin there was a paladin inside i got him to repair my Armour for me but realized it had cost and insane amount so i went to go and reload the game save and BAM!!! got hit with the missing DLC glitch. I have tried many times to restart it this does not work and i have also tried using a passed save which did not work. so looks like my only option is to start over from the beginning :banghead: :banghead: which is something i really do not want to do so if anyone could tell me if there is a way i could get my save file to work again please let me know otherwise i dont think i will be playing this game until a patch comes out to fix this very annoying problem

It's a bug.

Patch is coming out "soon" apparently.

Manual save alot too, Prevents this from happening.