In the code snippet you provided I see that you're setting only three of the four threshold values which means the threshold you don't set gets an automatic value which may be causing the problem. Another problem may be the actual size of the content you want to switch with these thresholds - have you checked what is the actual size (and thus are the threshold values correct) of the content you want to swap? Sometimes when you don't hard code the size of your elements it may be tricky to determine the actual size with which they're rendered. You may need to check their size at runtime.
Alternatively, you can swap the visible content of the FluidContentControl manually as the tile states change. To do that, you need to set the ContentChangeMode of the FluidContentControl to "Manual". Also, you should attach to the TileStateChanged event of the TileView and do the following:
private void tileView_TileStateChanged(object sender, Telerik.Windows.RadRoutedEventArgs e)
RadTileViewItem item = e.Source as RadTileViewItem;
if (item != null)
RadFluidContentControl fluidControl = item.ChildrenOfType<RadFluidContentControl>().First();
if (fluidControl != null)
fluidControl.State = FluidContentControlState.Large;
fluidControl.State = FluidContentControlState.Small;
fluidControl.State = FluidContentControlState.Normal;
Let me know if any of the above suggestions helps.
the Telerik team