Obstructing noise patterns cover the entire scenekit scene when a node is selected.
I reinstalled Xcode, created new project, new scenekit scene, same problem.
Xcode Version 11.3 (11C29)
macOS Catalina Version 10.15.2 (19C57)
MacBook Pro (13-inch, 2019)
I have exact same problem, same hardware, same macOS with you.
I think this problem might be hardware or macOS issue.
I have 2 iMacs and MBP 13" 2019 (4 ports), This problem only occurs at MBP 2019 (13")
So I think this is a Display issue.