Change order or adding to a PO that is attached to a requisition not being complete

Summary

PO that have a change order or that a line has been added to them, his not being completed even tough that the approval have been granted

Content

We currently have the issue that when the buyer is trying to add to a PO that already have a line from a requisition, or that he made a change on the order, it goes to the correct workflow and is being approved but when we go to see on the PO, its still in pending approval stage.

 

Does any of you have had this issue and knows how to resolve this.