Tap on a tile to execute its navigation or rather some JavaScript. Expected behavior is for the click event to fire. Actual result is that the tile's drag is initiated - the DragStart event on the tilelist fires and the tile gets the big z-index, and you can drag it around. This behavior does not manifest when there is only one tilegroup.
Setting EnableDragAndDrop to false will alleviate this, but will remove the drag-and-drop functionality.