BSP object position bug.

I am trying to use object position input node for material that I am using for many BSP objects. I want to create some per object unique randomization but it seems that all BSP objects use same value.
I definetly see it changing when I move some BSP brush but same object position is given for all objects. I also tried to use actor position but that input node always give zero. Is this bug or intended? Is there some other randomization input that I could use for BSP?