Hello,

Currently, I need more time to discuss with our developer teams. I will let you know asap when I got response,

Regards,
Handy

Hello, 

Please try to use this code snippet and let me know if you still have trouble in UXPopUp or not.

  static MainPage()
  {
            EventManager.RegisterClassHandler(typeof(UXPopup), UXPopup.ClosedEvent, new ISRoutedEventHandler(OnClosed)); 
  }
  private static void OnClosed(object sender, ISRoutedEventArgs args)
  {
            args.Handled = true;
   }

Regards,
Handy

Hi,

Unfortunately, due to other high priorities and urgent issues, we have to shipped SP1 earlier than expected. As the results, the SP1 doesn't include the particular work items associated to your issues. We will continue to address the rest of work items in the upcoming hotfix based on our work items queues and priorities. Thank you for your understanding in this matter. SP1 would be release in the short time.

Regards,
Handy

Hello Dasha,

Unfortunately, due to other high priorities and urgent issues, we have to shipped SP1 earlier than expected. As the results, there are several priorities that need to be changed. I am apologized that we did not focus to test in SharePoint environment. We are not quite familiar with SharePoint environment.
Perhaps, you can help us to avoid wasted times by providing a simple video to show step by step to replicate the issue (integrating to sharepoint and import webpart to Sharepoint library, settings, etc).
Once we are able to have the same result in here, we will forward this to our development teams.
Thank you for your understanding in this matter. Once again, I am very sorry that we are very late to assist you.

Regards,
Handy