the cmaskingID element looks half element-ish and half diffuse-ish.
Tech info:
3dsmax 2016
corona 1.7
Distributed Rendering through batch render.
It looks like it’s mixed with sampling focus, or something similar. Can you send us the scene?
We have just released Corona Renderer 1.7 Hotfix 1: Renderer for architectural visualization - Corona | Chaos
It contains some important DR fixes, so please download and install it.
Please make sure that Corona Renderer 1.7 Hotfix 1 is installed on all computers, and that DR server 1.7 Hotfix 1 is running on all of the slaves.
If the issue will remain after installing this version, please contact us, and we will continue looking for a solution.