Sea / ocean material, bump and displacement not showing

OK - So I am trying to create a PBR material for seawater surface for a boat project.
As I am new to both Rhino7 native render and PBR materials, I am shortcutting the process, by following the excellent tutorial by Tom Budd:

Everything is OK up until adding bumpy texture to the material.
The viewport rendering mode shows a bumpy surface, but rendered preview show only flat surface.
I have tried dozens and dozens of variations of mapping size and -type, no difference.
Adding the same turbulence texture as displacement map is the same: Shows in rendered viewport, but not in rendered preview.
What am I missing?
Is there a bug? Where? GPU?

Viewport screendump:

Render preview screendump:

Thanks in advance for any suggestions


Here a couple of posts to look at

The first and third linked posts have water materials available in them for your benefit.

addendum: what you see in the Rendered viewport is just the bump map. Displacement doesn’t work too well on the ground plane as displacement maps needs a lot of dense geometry to be useful. Anyway, the above linked posts should help you get good results using normal maps.