G-buffer Material ID will not render out

I am trying to render out a Material ID G-buffer channel saved out as a seperate saved channel and it does not seems to work. I can render it out in the Vray VFB and I can see it, and I can render out other g-buffer channels as separate files, but Mtl ID does not seems to work. Nothing is saved out at all. Anyone have an idea why?

Jeff Mottle
CGarchtect.com/Element2

Anyone?

I get the same, probably should be posted in the bugs section.