SwiftUI Mac navigation title is not editable

I have a SwiftUI application whose primary scene has the simplified definition:

WindowGroup(id: someID, for: SomeModel.self) { $id in
    RootView(id: $id)
}

The body of RootView includes:

someView
    .navigationTitle($title)
    .navigationDocument(model)

The navigation title displays the correct value, however according to the documentation of the above modifiers, the navigation title should be editable and include a proxy icon. Neither of these is the case.

• RootView does not include a NavigationStack nor a NavigationSplitView.
• The Transferable implementation of the model is correct since drag & drop work fine. The UTType for the model conforms to public.content but not public.data since the model does not represent a file.

Have I overlooked something in the implementation or is this a bug in the current beta?

Xcode: Version 14.0 beta 6 (14A5294g), Feedback: FB11402796.