I feel like I am being really stupid using Rhino 8.5.24058.13001.
Bump map applied in Custom material… looks set.

Bump map is translated correctly by Rendered…

Bump map is translated beautifully by bella (which isn’t even required here), even if the scaling differs…

Go to Cycles (Raytraced)…
GONE?!

What am I doing wrong here? Is custom material special in some way?