Env volume Fog.

[stezza]

OK folks.I'm stumped.

Why can't I see a solid green fog in the volumetric cube.

I have used a volume primitive cube and replaced the default fog shader with the VRayEnvironmentFog

Cant cant get it to work.

Here is the scene file for you to play with - Can anyone work out why?

[hermit.crab]

Fog containers are not supported (footnote n13) on GPU, I'm afraid.
Instead, set the VRayEnvironmentFog in the Environment Volume settings (Render Setup> Overrides > Volumetrics); create a regular object with an opaque VRayMtl and drag it onto the VRayEnvironmentFog's set.

FYI: I've added your post in the improvement request (internal bug-tracker id: VMAYA-8352) for their support.