See the attached image.

Steps to reproduce:
1. I checked the checkboxes 'Product' and 'Price'. The Product field added to row labels, and price to values.
2. Unchecked the 'Price', the price field removed from the pivot.
3. Unchecked the Product, doesn't  remove the products from the pivot.

Add filtering support for the aggregate descriptions (PropertyAggregateDescription).

Currently, there is such feature for the row and column group descriptions.
https://docs.telerik.com/devtools/wpf/controls/radpivotgrid/features/localdatasourceprovider/filtering

When the ItemsSource of a LocalDataSourceProvider is null initially and than set to a new value, the FieldListViewModel of the inline field list is not refreshed.