Hello Peter,

Thank you for posting in Infragistics forum.

Can you please try adding HorizontalAlignment setting to the Rectangle object in your marker template and see if it fits your requirement?

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        private static DataTemplate GetMarkerTemplate(string color, Presenter viewModel)
        {
            DataTemplate template = new DataTemplate();
            double heightAndWidth = 7;
            FrameworkElementFactory gridFactory = new FrameworkElementFactory(typeof(Grid));
            FrameworkElementFactory rectangleFactory = new FrameworkElementFactory(typeof(Rectangle));
            //Set HorizontalAlignment=Left.
            rectangleFactory.SetValue(Rectangle.HorizontalAlignmentProperty, HorizontalAlignment.Left);

.....
        }
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