Can't mod weapons in New Vegas

I just bought a scope for my hunting rifle and when I moused over it and pressed x nothing happened. The option to mod it isn't grayed out, and I've tried buying other weapons and mods and they didn't work either. I know it isn't a gra/non-gra issue, and I can't think of anything else. I only have a couple mods for the game, and I tried disabling them with the same results. Does anyone know how to fix this?

Edit: I forgot to include the mods I use, I have NVSE as well as a mod that lets you smoke cigarettes (https://www.nexusmods.com/newvegas/mods/49677) and one that gives you the wild wasteland trait for free (https://www.nexusmods.com/newvegas/mods/35653). None of these edit/add weapon mods so I don't think there should be a conflict, but I removed them (NVSE included) and made a new character and still couldn't mod weapons. I validated my game files (I forgot that was an option or I would have tried that before making a post) and it said that one failed to validate and will be reaquired. I validated them again after it finished downloading and got the same results multiple times. I imagine this is the issue, so I'll be doing a fresh install. If the issue persists I'll update the post.