I think it is a weird cache thing within the builder. The app running on an iPhone is never effected, just the builder. I took your advice and when it happens I switch back and forth between apps (really different versions of the one app) and it ‘seems’ to clear up after a few switches. I also tried switching tabs and switch “View As” to no avail but exiting and entering the app within the builder seemed to work…eventually.
The only REALLY weird thing was when I switched from Chrome to Safari I still got the spinning of death.