modal view showing up empty in IOS 14

Possible solution is to separate content of sheet into dedicated sub-view, like below.

Tested with Xcode 12.1 / iOS 14.1

struct ContentView: View {
    
    @State var modalIsPresented = false // The "settingsView" modally presented as a sheet
        
   @State private var modalViewCaller = 0 // This triggers the appropriate modal (only one in this example)

    
    var body: some View {
        
        NavigationView {
            VStack {
                Spacer()
                Button(action: {
                    self.modalViewCaller = 1 // SettingsView
                    self.modalIsPresented = true
                }
                    ) {
                        Text("Tap to present Modal")
                     }
                Spacer()
            } // END of main VStack
            .onAppear() {
                self.modalViewCaller = 0
            }
            .navigationBarTitle("Test app", displayMode: .inline)
        } // END of NavigationView
        .sheet(isPresented: $modalIsPresented) {
            SheetContent(modalViewCaller: $modalViewCaller)     // << here !!
        }
        .navigationViewStyle(StackNavigationViewStyle()) // This avoids dual column on iPad

    } // END of var body: some View
  // MARK: @ViewBuilder func sheetContent() :
}

struct SheetContent: View {
    @Binding var modalViewCaller: Int
    var body: some View {
      if modalViewCaller == 1 {
            SettingsView()
                 .navigationViewStyle(StackNavigationViewStyle())
                 .onDisappear { // This always triggered
                      print("onDissappear triggered ! at \(Date().debugDescription)")
                      self.modalViewCaller = 0
                 }
            }
    }
}