I turned off the option to display curves when rendering ( see attached ). Now I
cant ‘turn’ them back on, as they are greyed out.
Is there some other setting i need to have set to enable them again ?
Found the answer myself - in Flamingo Help
"Display in rendered viewports
Note: These settings only affect viewports using Rhino’s Rendered display mode. To see these objects in a rendered image, use Post Effects."
A strange way to do business - but there must be a reason.
All good now