There are large number of items for the TreeList (for example 3000) and you have all them initially collapsed. For example you could modify the IsExpandedBinding demo to have 3000 items. Then scroll down so the row with Drinks and Count = 2194 is at the top of the control and expand it. The result is that both that row and the row with Drinks and Count = 2199 expand.
TreeListView is trying to expand its item which is empty.
As a workaround you can try executing the selection in a Dispatcher with DispatcherPriority.Render. This may not apply in the case when there are many nodes outside the View area.
workaround: Extract the ControlTemplate for the TreeListViewRow and set the Style explicitly or remove the local Style setter.
If you move an item from one level to another into the tree, the indent of the corresponding row won't get updated. This is reproducible only if the new parent of the moved item is expanded, while the operation is executed. Usually, this can be reproduced by calling the ExpandHierarchyItem() for the new parent item method just after the moving of the original item. To resolve this you can delay the expanding of the item. Note that the expanding is executed manually by calling the ExpandHierarchyItem() method. So, you can use a dispatcher with a lower DispatcherPriority to delay this. Or alternatively, you can collapse the item before expanding it (using the CollapseHierarchyItem() method).