As I understand, “Ordered Qty” should display Qty ordered (through purchase order) based on a particular sales order.
This displays correct picture only for “Drop Ship” type items. Because it seems that PO item is directly linked with SO item only in case of “Drop Ship”. In normal course, SO item is linked with MRQ Item. And MRQ item is linked with PO Item. So, in normal case (Non-drop Ship), ordered qty displays zero, evenif it is created on the basis of a SO (Via Material Request route).
There should be ways to link PO with SO in either case (Drop Ship & Non-drop Ship) so that Order Qty should display the value in either case.