Hello,
Thanks for your response.
I export from viewports on sheet layers and saved views, this is where the problem is happening. I currently don't export directly from from the design layer, so I will have to give it a test.
The frustrating thing is, after 30 exports, vectorworks is now exporting correctly, without any tweeks or alterations from me. So I'm back to 1/3 being a white or black render. I will do further tests are you suggest using wireframe etc and I will post the results on here.
Greg