flickering in Matte and reflections

[bennyboy]

Hi, I've mentioned this in another related post but this issue has only popped it's ugly head again until now. I'm rendering a scene with a shadow catcher and am getting flickering in the shadow and also in some seemingly unrelated reflections. Using Rebus render farm. Settings are pretty basic. LC for secondary bounces. Using 3ds Max 2018, and Vray Next.
Here is a link to a sample of the animation:
https://youtu.be/GXfIRyWQpQo
I can send Chaos support the file upon request.