Wokraround: Set the Selection property in the constructor of the window using the SelectionRange<T> struct.

public MainWindow()
{
    InitializeComponent();
    this.radSlider.Selection = new SelectionRange<double>(11,16);
}

This is reproducible when the deferred dragging is enabled and the slider is defined in a template (DataTemplate or ControlTemplate). The selection values are correct, but the UI of the selection is not properly updated. 

To work this around you can subscribe for the Loaded event of slider and reset its IsSelectionRangeEnabled property.

private void RadSlider_Loaded(object sender, RoutedEventArgs e)
{
	radSlider.IsSelectionRangeEnabled ^= true;            
	radSlider.IsSelectionRangeEnabled ^= true;            
}

When the slider is placed inside a ScrollViewer and the scrollviewer is resized fast a "Layout cycle exception is thrown".

The original scenario where we reproduce the exception is the following:
SelectionStart, SelectionEnd, Minimum and Maximum of the Slider are bound to DateTime.Ticks via converter.
Exception is not reproduced if you move the Mininum declaration in xaml before the Maximum. And same for SelectionStart = before SelectionEnd.

We are closing this item due to the workaround and the fact that it is NOT reproducible in WPF.

If your scenario is different, please open a new support thread with more information regarding this exception.

When the Slider ControlTemplate is edited in Blend, the ticks of the control are not displayed.

Workaround:
The ItemsSource and ItemTemplateSelector of the RadTickBar controls "BottomTickBar" and "TopTickBar" is not set in the extraction process. To workaround this, set these two properties of TickBars and the ticks will be displayed ", for instance:
ItemsSource="{TemplateBinding ResultTicks}" and ItemTemplateSelector="{TemplateBinding TickTemplateSelector}".

Reason for closed:
This is an issue, that has been reported to Microsoft on several occasions (for example here: https://connect.microsoft.com/VisualStudio/feedback/details/677461/msdn-forum-the-value-of-itemscontrol-itemssource-is-missing-in-the-extracted-template )  and it is not scheduled to be fixed.

When you have set the value of the RadSlider to the maximum available and have placed the control within another element, lowering the width of the parent control does not cause the RadSlider to shrink as well.

When the slider is hosted in a TabControl its bindings don't work as expected when switching tabs

Fixed in Q3 2014