Yeah, we're seeing this crash too. Seems to be iOS 15 related as it's affecting our app that was built against the iOS 14 SDK so I assume a bug that will be fixed.

@tarbayev I know this has been a while but does this workaround still work? I found the real XCPreviewAgent for the active simulator, copied its bundle id com.apple.dt.XCPreviewAgent and created a new iOS app on the same simulator with the same bundle id. Built and ran it on the simulator but it didn't appear to use it when running previews. Also tried swapping out the XCPreviewAgent app bundle with my version in the Preview device folder and this didn't work either. I've got a but that happens on Previews but doesn't happen on the exact same code on Simulator and I'm wanting to debug the Preview to see what is going on. This is quite frustrating.

No unfortunately not, I think it's an issue of the Simulators which are where the frameworks are located missing the symbols or Instruments not indexing them. When debugging on device it's fine, though I still don't see SwiftUI symbols.