To reproduce: add a RadDiagram and use the following code snippet:

this.radDiagram1.PanToPosition(new Telerik.Windows.Diagrams.Core.Point(10,10));

Workaround: subscribe to the Pan event: 

this.radDiagram1.Pan += radDiagram1_Pan;

        void radDiagram1_Pan(object sender, Telerik.WinControls.UI.Diagrams.PositionChangedRoutedEventArgs e)
        {
        }