Mahapps.Metro对话框未在Command.Execute中显示

Question

我想在做一些工作时显示“加载”对话框。当我通过按钮单击事件触发作业时，它正在工作（主窗口显示为灰色，对话框显示为模态）。

XAML：

<Button Click="ClickButton" ... />

观点：

private void ClickButton(object sender, RoutedEventArgs e)
{
   var dialog = this.Resources["MyDialog"];
   this.ShowMetroDialogAsync(dialog as BaseMetroDialog);

   ... do the work
}

但是当我使用命令时

<Button Command="{Binding MyCommand}"

并在命令Execute method

中调用该对话框

public async void Execute(object parameter)
{
   MainWindow metroWindow = Application.Current.MainWindow as MainWindow;
   var dialog = metroWindow.Resources["MyDialog"];
   await this.ShowMetroDialogAsync(dialog as BaseMetroDialog);

   ... do the work
}

主窗口只显示灰色，没有显示对话框。