I might've had the same issue back then (not sure anymore) and somehow fixed it, but I don't remember how.
The other thing is that some years ago I played the game with all the mods I'm using now, but for some reason it doesn't want to work now. I've installed NVSE, used FOMM and NMM, launched the game with the launcher the first time and even started a new game before modding, I haven't changed anything in the ini file, I've used FOMM to invalidate the archive, I've tried manually installing the mods and I've even reinstalled the game, steam, FOMM and NMM multiple times even going as far as to try other install directories. The DLC loads, but the mods don't, even though they are 'recognised' by FOMM,NMM and the FNV launcher itself. I've had this annoying issue where I downloaded mods perfectly like I was told and for some reason the game doesn't load them.