i have a strange problem with my current project. As soon as i enable my road or river the volumetric fog and the volumetric clouds are completly gone. I have attached 3 Screenshots.
Here in the first image the road is disabled and the volumetric fog is working as intended.

In this image i enabled the road and the fog is gone.

This is the material for the road.

I hope that someone can help me with that issue.
Greetings