The Gridview Distinct Filters can't be reuse if the filtering panel is close.

When the filter panel is reopen selecting or deselecting distinct filter have no effect.

This is reproductible in telerik demo in any gridview with distinct filter.

the bug is present in browser and oob applications.

The vertical scrollbar of the RadGridView control disappears when hosted in a RadExpander control with its ExpandDirection set to Right. Initially the scrollbar is shown but if you collapse and then expand the expander control, the scrollbar is missing.

To work this around, stop the RadExpander's animation.
<telerik:RadExpander telerik:AnimationManager.IsAnimationEnabled="False" />

This is reproducible in the Paging Before Grouping demo. If you remove the grouping by the Country column by clicking on the X button of the group, the indent of the group expander will not be collapsed. See the attached video. Note that this reproduces only once when the example loads.

reproducible in themes where foreground of cells is changed on selected (i.e. VisualStudio2013)

Workaround:
add cell template to the column

<telerik:GridViewDataColumn.CellTemplate>
    <DataTemplate>
        <TextBlock Text="{Binding Property, Converter={StaticResource converter}}" />
    </DataTemplate>
</telerik:GridViewDataColumn.CellTemplate>

The issue is replicated only when a filtering operation is applied. For a grouping and sorting one it is not. In Silverlight when the new source collection is set, the column headers are cleared and empty rows are displayed. In WPF the item is not cleared. The workaround is to clear the FilterDescriptors collection of RadGridView before assigning the new instance of the source collection.

GridViewExpressionColumn cell does not update its content when editing it, CellEditTemplate is used and the datacontext is an object which implements IEditableObject interface.

The problem should be resolved with lib version 2015.3.1026.