I think using lazy loading (loading the layout in the CLV.VisibleRangeChanged event) is stopping the selection color showing . Might be wrong.
Any way have added CLV Selections class to the sample and selected items now display as expected .
This class extends xCustomListView library and adds more selection modes: MODE_SINGLE_ITEM_TEMP - The same as the default behavior. MODE_SINGLE_ITEM_PERMANENT - Single item is selected and the selection remains. MODE_MULTIPLE_ITEMS- Multiple items can be selected. There is also a helper method...
I have set it to 'Permanent' mode but you can change it to suit.
I have commented where any changes have been made.