Buyer Disappears from Requisition Line in iProcurement

When creating a requisition in iProcurement we are encountering an issue where if a user adds some items to their cart, closes the application and comes back the next day to add more items to their cart, buyer name disappears from the requisition line. The requisition then gets stuck until someone queries it in the PO module and manually adds the buyer. Has anyone else encountered anything like this and if so how did you resolve it?