In the new WIP 6.0.17234.9201, 22/08/2017, the transition from GL to cycles isn’t working nicely like it used to - now its cutting from the GL view to solid white and then fading the cycles view in.
On the upside, the banding/ice sculpture problem is fixed
I’ll investigate this next week. I’m close to finalizing a merge from upstream Cycles, and I probably won’t have time to check this out before the end of the day.
That said, I haven’t seen this behavior in my local builds with the merged code.
For the record, with what GPU are you rendering? Is it also the GPU driving your display?
Its happening on my work and home PC’s. Work is a GTX1070 and home a GTX980 - both PC’s only have the one card.
The last time this happened, I was able to fix it by clicking Restore Defaults in the Display Mode options, but that hasn’t worked this time. There is something a bit weird about Restore Defaults too - I click it on the Raytraced and all sub items (Grid, Objects etc), then OK on the options dialog. Then I go straight back to Options, and now Raytraced is in bold blue and Objects is blue.
Interesting. You can try renaming the settings folder under %APPDATA%\McNeel\Rhinoceros\6.0 to something different. Renaming to ensure you still have a copy of your current settings.
Further under the Plug-ins folder look for RhinoCycles (9bc28e9e-7a6c-4b8f-a0c6-3d05e02d1b97) and rename the settings folder contained therein.
Once done with the rename actions you can start Rhino to see if everything default helps.
After installing today’s update, I tried renaming both the settings folder as per your instructions and started Rhino, but it didn’t help - it is still rotating with openGL then when I let go the mouse button, it goes completely white and cycles fades in over the white.
Hmm. I’ll install the other GTX tomorrow as well, to see if I can reproduce.