Have you tried restoring the display mode to its default settings? At the moment, I do not know what would cause this…but without the file, I can’t really see what’s going on, other than the pictures you posted. Which display mode is being used in those screenshots?
There’s a couple of us suffering from the same issue over in another thread:
I’ve tried resetting all the display modes but unfortunately it makes no difference. If there is a way to roll back the version of Rhino that would be great!
We have figured out what is causing this bug and have fixed and tested it. We plan to release an update to the 6.19 early next week with the fix for this bug.
In the meantime, you can work around this bug in two different ways:
(Recommended) In Rhino 6 for Mac 6.19, when you start Rhino and begin a new modeling window, you can run TestToggleBuiltInFrontFacing. You will need to run this each session.