I didn't check but I am beginning to suspect the body that is part of the hip face-hugger doesn't have a belly node.
Either we will have to add a belly node to that model or figure out a way to make the critter a standalone mesh without the body part.
Also, for this parasite, the belly is supposed to grow over 5 days. Make sure to wait that long when you test it.
I've already done that. I'll make a quick patch for it right now and upload it asap.
EDIT: Here we go. I only erased the body itself and changed the facehugger's slots to the chastity belt slot.
Mind you, there a