Why won't my Gameplay Camera occlude Character Meshes?

So here's the setup:

Gameplay camera setup for Animal Crossing-style conversations, all set up and working

Add Occlusion Material node with totally alpha'd-out material, set occlusion radius to 5,000 (just for testing purposes) and set Occlusion Test Channel to Camera

Double-check collision data on characters, all meshes block the Camera channel

Camera system now occludes floor, objects around characters, but occludes neither the in-focus character nor the player!

It's driving me crazy - I've tried everything I can think of, it just won't occlude the damn characters.