I'm sorry for the misunderstanding and could I please ask you to tell us how exactly are you using the RadTileView? Do you use it databinding scenario or with XAML defined items, how do you use the HeaderTemplate and the bindings? It'll be best if you could send us some code snippets or a sample project.
In order for my previous workaround to work you'll have to update it a little bit:
var tmpItem =
var tmpHeader = tmpItem.Header;
tmpItem.Header = tmpHeader;
Another possible workaround includes custom controlTemplate and I've attached a sample project showing this.
If you need further assistance please feel free to ask.
the Telerik team