The reason for this behavior is that the IObjectScope instance that is used for retrieving the persistent object is not the same as the IObjectScope instance used to bind the GridView.
You could use the following approach to work with the correct IObjectScope object:
IObjectScope scope =
MyPersistentClass result = scope.Extent<MyPersistentClass>().FirstOrDefault(x => x.ID == 1);
Hope that helps.
the Telerik team