If you have WriteOnly property in your Data Item and you set a collection of DataItems as ItemsSource of LocalDataSourceProvider, RadPivotGrid and RadPivotFieldList will not show any data.
In OLAP you are able to define ragged hierarchies. In a ragged hierarchy, the logical parent member of at least one member is not in the level immediately above the member. This can cause branches of the hierarchy to descend to different levels. RadPivotGrid doesn't show them correctly.