I face the same issue: Can't import RealityKit on Xcode Version 13.0 beta 4 (13A5201i) When I went back to the beta 3, Make sure I'm opening the Xcode 13 Beta 3 Clean the build folder by shift + cmd + k or Product/Clean Build Folder (Optional) Delete the contents in /Users/YOURCOMPUSER/Library/Developer/Xcode/DerivedData Then, I can compile the app with Xcode 13 Beta 3 again Hope this help

Intel based Mac: No Freezing M1: Freezing

Me too