Not sure what i did, but this is what I’ve been left with.
I was moving focus between Rhino and Safari. While in Safari, I think I moved the 3Dconnexion SpaceMouse, which often still seems to control Rhino, when I moved the cursor back to Rhino and over the Perspective View, the items in the drawing followed the cursor while disappearing into the distance.
The top view functions fine. If I select an item and use ZSA I get the message “Unable to zoom some views - no objects are selected”. Selecting different views and repeating ZSA I managed to get back all but the Perspective View, but then I moved the SpaceMouse and all views are blank! Other files seem fine. I’ve exited Rhino, and rebooted the Mac, but still the same problem.