Glass not passing Material ID anymore

V-Ray V-Ray for 3ds Max General
1

Hi all, going nuts here.

Trying to use a glass material for internal windows of an arch viz render. I need the glass to be invisible to the material ID of what is behind.

My material from my library, which I swear was working has settings:

reflect: Affect channels: color + alpha
refract: Affect channels: All channels

What am I missing? What else can muck this up?

VRAY 3.00.01

2

I’ve had this issue before, try setting your reflection to only affect colour.

3

Thanks for the suggestion - did not work. Really stumped.

4

I just had this problem too.
Have you tried this?.. Create a new material, fully reflective, fresnel ticked, and 100% refractive. Affect channel settings as you have them. Does that work?
If you have any fog in the glass I think this can mess things up, but it’s a good idea to start with a default glass material and then re-apply your adjustments one at a time until you break the transparency-to-ID-ness of the material.