So this has happened to me once before, but I can't remember how I fixed it.

Right now, I can cast any single-handed spells fine. But if I try to cast a spell like Dragonhide or Mass Paralysis, I can't do it from the first person. I have to cast those from third-person view.

Note: When I try casting those from first-person, the magicka drains and the sound effect leading up to casting happens, but the cast won't happen.