Refraction and Fog color problem

Hello,

I am working woth vray 3.6 and 3ds max 2018
As you see in the image, I get those “red lights” with all the objects that have refraction in my scene.

The material is a “Vraymtl” with all default parametres, except for the fog color. The multiplier is less than one, and the color is just a bit saturatet.
This problem is less noticeable but also apreciable if the fog color is almost white.

It is an interior scene, and this only occurs inside the “room”. If I put those objects outside, they behave as expected.
It also “follows the sun”, so if I change the position of the sun, they also turn around following the sun…what I mean, is that if there where no walls there, the “red lights” would be the “normal” shadow of the object

The problem dissapears if I turn off the “affect shadows” of the refraction section of the material…the point is that never happened to me before, and I wonder if this is a normal behavior of vray that I never noticed before, or not??? I am missing something very basic??

I tryed to reproduce this behavior in a new file, and it happens with all new and “simple” files, with just one object inside a room …it looks likes the less light is getting inside the room, the “red lights” get stronger

Caustics are off, and sun is by default, rendering configuration by default…any advice??

Thank you!
(and sorry for the double post)

Would it be possible to send us a sample scene, where the issue is present to support@chaosgroup.com? Please mention this forum thread.