I have the same issue during developing iOS app with Xcode 12 beta 2 for iOS 14 version... I don't know what the reason is, and when I test above code in my Xcode 12 beta 2 but it didn't reproduce... It must be a bug of SwiftUI , I think.... I didn't test my project in the real iPhone, but only in simulator yet.

I tested the project in Xcode 12 beta 2... It worked without those errors... It's only issue for Xcode 12 beta 3 until now...

Maybe I found the reason of this bug... if you use iOS 15 (not found iOS 14), and you write the code NavigationLink to go to same View in different locations in your projects, then this bug appear. So I simply made another View that has different destination View name but the same contents... then it works.. you can try.... sorry for my poor English...

In my case, I solved this problem by removing usb relevant app from Settings>General>LoginItems. After restarting, then Xcode recoginized my iPhone as a development device. Before being solved, my other old iPhone worked and iPad was also worked. Only my main iPhone didn't work. but It solved now for all.