When RadMap is used within a popup and the map provider is assigned each time before the popup is opened then UI hangs when it is opened second time.

Workaround:

The problem occurs when the RadMap.Provider property is assigned second time when the popup is opened and then it is closed. You can assign this property one time only to avoid this problem. You can do it from a XAML code. Or you can check that the provider is already assigned in the codebehind like following:

private void MapButton_Click(object sender, RoutedEventArgs e)
{
    if (radMap1.Provider == null)
    {
        radMap1.Provider = new OpenStreetMapProvider();
    }
 
    PopupPosition.IsOpen = true;
}