@BrianJ - I am having this problem.
Using Version 6 (6.18.19266.13352, 2019-09-23)
Was in ExtractMeshPart - clicked on object in Perspective viewport and it went black.
This is what I get when I switched to Wireframe
When I switch back to Rendered it is still black.
@kalmdown The first thing I’d check is if the Rendered display mode is set to defaults in Preferences > Display Modes. Then if it is, do you have any additional Rhino 6 for Mac documents currently open you can close? If not and you still have this issue, please upload the 3dm file and the steps to reproduce it and I’ll take a look. You can also email tech@mcneel.com instead if you like. Lastly, please send the results of the SystemInfo command in Rhino 6 in your reply.
It looks like an issue with the Rendered display mode with the Radeon Pro 455 but I know of other users on the same OSX build who have that GPU and haven’t run into this so it may be system specific or file specific.
