Hi Greg Duffield,
The Virtualization of the RadTileView is meant to be used with ItemsSource, Bindings, DataTemplates and etc. and not with XAML defined items. That's why if you try to use it with XAML defined items you'll lose the Headers. If you use it with binding and DataTemplate you should not have any problems.
Also you may try to turn off the Virtualization and see how the application behaves, because I'm not sure it will make any difference if you have only 12 items.
I've attached a sample project for you to examine.
the Telerik team
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