I tested with just visualoverhaul-1.0.0, fabric-api-0.29.1+1.16, and autoconfig1u-3.3.1 installed.

Are you using any additional resourcepacks?
It's made using minecraft's predicate system, so it will not work if a resourcepack overrides the disc models.
I know it's not ideal, but I couldn't think of doing it another way.

Oh yeah it works if I disable all my resourcepacks, guess one of them was changing the discs without me realizing it.

Is there a reason you can't just provide your own models+textures independent of the normal disc textures?