I don’t understand what is happening here… In case somebody has an idea…
This is happening inside Rhino6 (“Rhino Render” mode) and inside Rhino7 (“Legacy Rhino Render” mode).
Rhino 7 in “Rhino Render” mode works OK.
The plugin has its own material → converted for Rhino via override void SimulateMaterial(…)
The viewport shows the material correctly but the mat preview doesn’t show the texture only the diffuse color.
I can not understand why it doesn’t show the texture.
It is interesting that when I rotate the material preview (via mouse), during the rotation it shows the texture
when I release the mouse it is again the grey sphere.