MessageDialog确认在Windows 10移动版中不起作用，但适用于Windows 10

Question

如果用户想要在我的AppViewBackButton

中使用以下代码按下后退按钮（硬件或App.xaml.cs）时想要离开页面，我会要求确认

protected override void OnLaunched(LaunchActivatedEventArgs e)
{
  ...
      SystemNavigationManager.GetForCurrentView().BackRequested += OnBackRequested;
  ...
}

Private async void OnBackRequested(object sender, BackRequestedEventArgs e)
{
    Frame rootFrame = Window.Current.Content as Frame;

    if (rootFrame.Content.GetType() == typeof(GamePage))
    {
        var op = await ShowAsync("Do you want to exit?", "Exit?");

        if (op == MessageBoxResult.OK)
        {

            rootFrame.GoBack();
            e.Handled = true;
        }
    }
    else
    {
        if (rootFrame.CanGoBack)
        {
            e.Handled = true;
            rootFrame.GoBack();
        }
    }
}

public async Task<MessageBoxResult> ShowAsync(string messageBoxText, string caption)
{
    MessageBoxResult result = MessageBoxResult.None;

    MessageDialog md = new MessageDialog(messageBoxText, caption);
    md.Commands.Add(new UICommand("OK",
         new UICommandInvokedHandler((cmd) => result = MessageBoxResult.OK)));


    md.Commands.Add(new UICommand("Cancel",
        new UICommandInvokedHandler((cmd) => result = MessageBoxResult.Cancel)));
    md.CancelCommandIndex = (uint)md.Commands.Count - 1;


    var op = await md.ShowAsync();

    return result;
}

问题是var op = await md.ShowAsync();没有等待结果。该应用程序短暂显示对话框，无需等待任何输入，只需关闭应用程序。

我目前没有测试我的Windows 10移动设备，因此我正在使用模拟器进行测试。模拟器或代码有问题吗？

此代码在我的桌面上运行良好。