I'm experiencing the same issue with Xcode 12.1 and all newer versions. It happens ONLY on my second monitor (configured as my main monitor). It does NOT occur when I open Xcode on the integrated monitor of my MacBook Pro. The crash occurs in the "Behaviors" menu and when trying to "Manage Schemes". I attached a crash log for one of the cases. My fix for now is to move Xcode over to the integrated monitor before opening one of the menus. XcodeCrashLog.txt - https://developer.apple.com/forums/content/attachment/a7bf1100-6255-4a13-91cb-04b3aed239a8