Thanks. This all makes sense. I tweaked the view angle properties to 1 deg and it now shows the smooth surface... Of course I now understand that it does not matter and that the surface and the resulting computation are correct.

The next problem I have is when trying to shell this surface (which I had done on other lofted surfaces) ; it does not seem to work here. I understand that shelling could be a problem when the (shell) thickness and the local surface radius are commensurate, but that should not be a problem here (using 0.05)...Ideas?

Tanks again for your help and a great software!