Cannot preview SwiftUI

I am somewhat new to Xcode and Swift and trying to figure out why I cannot see the previews in SwiftUI.
OS and Xcode are both latest non beta versions (macOS 10.15.5 and Xcode Version 11.5 (11E608c).

I have not even written any code, just created the default project (Hello World!) and then clicked the "Resume" in the preview.

It shows "Cannot preview in this file - Update failed".
Clicking on the info says "NewTest.app may have crashed. Check ~/Library/Logs/DiagnosticReports for any crash logs from your application." - but when I open the location there are no files.

I then try to run it in a simulator (defaulted to iPhone SE but works with any) and it runs fine.

The diagnostics show (start with) this:

Error Domain=com.apple.dt.UITestingAgent Code=-1 "failed to load library at path "/Users/xxxxxxxxx/Desktop/Swift/NewTest-ckvagdimpxrjjigjrqusmkwfddix/Build/Intermediates.noindex/Previews/NewTest/Intermediates.noindex/NewTest.build/Debug-iphonesimulator/NewTest.build/Objects-normal/x8664/ContentView.2.preview-thunk.dylib":

I tried several things per suggestions I have seen elsewhere but none have helped (Including complete re-install of Xcode, multiple restarts, deleting build folders and rebuilding etc.)

Seems like a fundamental issue but due to my lack of experience with Xcode I am not sure how to troubleshoot it.

The default project:

import SwiftUI

struct ContentView: View {
    var body: some View {
        Text("Hello, World!")
    }
}

struct ContentViewPreviews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}