Update: Before our change the GridViewGroupFooterCell content was right aligned and the GridViewFooterCell content was left aligned. We decided to unify them by setting default left alignment to both. This can be easily modified by changing the Column FooterTextAlignment property to Right or by using the following implicit styles: 

<Style TargetType="telerik:GridViewGroupFooterCell" BasedOn="{StaticResource GridViewGroupFooterCellStyle}">
    <Setter Property="HorizontalContentAlignment" Value="Right"/>
</Style>
<Style TargetType="telerik:GridViewFooterCell" BasedOn="{StaticResource GridViewFooterCellStyle}">
    <Setter Property="TextAlignment" Value="Right"/>
</Style>

The fix is available in R3 2017 of UI for WPF.

Full error message: No generic method 'Sum' on type 'System.Linq.Enumerable' is compatible with the supplied type arguments and arguments. No type arguments should be provided if the method is non-generic."

Showing in design time, working at run time. 

WPF Controls Samples -> GridView with Data Virtualization -> Edit UnitPrice and press Enter -> press ESC -> press Control+End.

Workaround: press ESC one more time or commit the edit before pressing  Control+End.
* works fine with QueryableCollectionView.

The problem can be reproduced only when the previously focused element is in ToolBar or RadToolBar. It is not reproducible in the default scenario. 

Should be resolved with lib version 2015.2.713.

GridViewColumnGroup.HeaderTemplate is not respected in Windows8, Windows8Touch and ExpressionDark themes. Instead, the name of the column group is its content.

This is reproducible with both StyleManager and Implicit Styles.

Should be resolved with lib version 2015.2.720.

Will be available with LIB version 2015.3.1026.

As a workaround, one can look this up by accessing the Object/DbContext directly.

Workaround is to specify that the format string should contain only the required member path:

<telerik:GridViewDynamicHyperlinkColumn Header="ID" DataMemberBinding="{Binding ID}" NavigateUrlMemberPaths="WebUrl" NavigateUrlFormatString="{} {0}"  TargetName="_blank"/>

A kind of a workaround for the user: resize any column/the entire window or collapse the row details.