The expanding of items does not work as expected in a data binding scenario when the CollapseAll()/ExpandAll() methods are used

There is a scenario where the RadTreeView is data bound and its items IsExpanded property is bound to a property from the view model. Then the CollapseAll() and ExpandAll() methods are called. When you try to collapse the treeview items through the property from their view model (that is bound to IsExpanded) only the items in the view port are collapsed.