Vector Pass turns materials black

Hi, I’m trying to add some motion blur to my scene in post to save some render time, and to do so I have to use a vector pass, however, when I turn the vector pass on, random materials show up as black in the render. This only happens when the vector pass is on, everything renders correctly when I turn it off. I also made sure it wasn’t a memory issue, and even when I only have one character on the screen being rendered, turning the vector pass on still causes parts of the character to show up as black (and it renders fine without the vector pass enabled.) Any idea of how I can fix this?

I don’t want to use 2 render layers because it doubles my render times and eliminates the point of me using post motion blur. So if anyone knows how to fix this please let me know, or if there is another way to add motion blur in post please let me know.

Thanks!

I’ve also posted this in Technical Support, but I thought maybe I can get an answer faster here.

EDIT: It appears that this problem doesn’t exist in the 32-bit versions of blender. However the 64-bit version is slightly faster and it would be awesome if this could get fixed.