I tested streaming data for nested property and the UI does not update. The data is updated in the collection bound to the DataGrid ItemsSource, still the UI doesn't.
When I enter editing the cell, the UI updates.
The issue happens in this case:
<telerik:DataGridNumericalColumn PropertyName="Address.Age"
HeaderText="Age" />
<telerik:DataGridTextColumn DataMemberBinding="{Binding Address.Age}"
HeaderText="Age DataMemberBinding"/>