When we have ListenForNestedPropertyChange property set to true and at some point Clear of the ItemsSource is called the newly added items to the collection stop to listen for PropertyChanged.
In order to make ListenForNestedPropertyChange work again toggle the value of the property. First set it to false and after that back to true.
As of Telerik v7.0.0 this started to happen. In v6.8.0 the issue doesn't occur. The customer uploaded a sample project in the support ticket.