Issues with VrayClipper

[Mr.Mxyzptlk]

I'm trying to clip these vray proxies so they don't come though the wall. Not sure where this grey artifacting (circled in red) is coming from. I have a green material assigned to the clipper itself.

[hermit.crab]

Hard to say from a single screencap. Could you simplify the scene and send it to us?

[Mr.Mxyzptlk]

Sent. Thank you Aleksandar.