Really weird issue with Polish's KillZombie Pistols Collection

Uthgard

Just discovered this: while the guns have a muzzle flash surface by default (with a few morphs and all the maps in the right slot in the surfaces tab) they don't appear on the render no matter what I do. I've even tried applying a stone shader to the surface, but it still doesn't show and here's the really weird thing: when I try to select the surface using the geometry editor, it doesn't pick up any polygons. It is as if by any intents and purposes, the surface doesn't exist, even though the outline is clearly visible when it is selected with the surface tool. I don't quite know what else to try, has anybody figured what's up with these ghost polygons?