NavigationLink selection not working as expected

I am probably missing something but I can't make the NavigationLink work inside a List.
I'm using NavigationLink(destination, tag, selection) And i would like to pop to the root view with a tap on a button as you can see in this sample project:

Code Block struct ContentView : View {
    @State var selectedView : Int? = nil var colors : [String]    = ["blue", "yellow", "green", "red", "black"]
    var body : some View {
        NavigationView {
            List {
                ForEach (colors.indices)
                {
                    index in NavigationLink (
                        destination : ColorDetail (
                            selectedView : self.$selectedView,
                            color : colors [index]
                        ),
                        tag : index,
                        selection : self.$selectedView,
                        label : {                             Text(colors[index])                         }
                    )
                }
            }
        }
    }
}
struct ColorDetail : View {
    @Binding var selectedView : Int? var color : String var body : some View {
        VStack {
            Text (color)
            Text ("SelectedView: \(selectedView ?? 99)")
            Button ("set SelectedView to nil and go back")
            {                 self.selectedView = nil             }
        }
    }
}

Why if I set selectedView to nil nothing happens? How can i pop to the root view (ContentVIew) from the ColorDetail on a button tap?

Just copy this code and try it, it will build.