I don't have that add on, but I have encountered this from time to time on other things. I found for me it has something to do with the emissions some Iray materials/shaders use. It happened today, I set up a scene, added a dildo prop and put an Iray shader on it, I wanted a jelly like look to the dildo so I used the Polyurethene Matte shader, I hit render and left to do errands. Come back a couple hours later and my figure had this same thing, the whole G8F was like this, and the hair was transparent. I was like WTF! I re-set up the whole scene, used the Matte Rubber shader and all was fine.
Iray is very finicky at times on how it reads the shaders/materials in the scene, I think it gets confused.