Render element issue of Vraybumpmtl.

[kiyeol_paek]

Render element issue of Vraybumpmtl.

I am using 3ds max 2025, vray 7.

I have a question about vraybumpmtl, one of the vray materials.

When I create a base material using vraymtl with a coat layer and add vraybumpmtl for additional bumps, I don't understand the output render element.

For example, when I use carpaint using a coat layer with bumpmtl, the coat layer render element becomes messed up, and I can't do the right work in post-production.

Is this a bug? Or is it an unavoidable part of the shader's characteristics?

If this output is normal, could you explain why?

[hermit.crab]

Thanks for the report. It seems the "Lock coat bump to base bump" option is always active when propagating a VRayMtl to a VRayBumpMtl. I've logged the issue (internal tracker ID: VMAX-14864). Not sure if there's another workaround except plugging the bump map in the VRayMtl instead.