Why is the Save for Later button disabled for Requistion change request when the requisition is alre

We are on PeopleSoft Financials/Supply Chain 9.2 PUM 19. Based on eProcurement role action settings, our users have the access to edit a requisition that has been sourced to purchase order. The edit to the fields allowed per the change template work as expected. However, the user would like to save the changes for later. We have commitment control turned on. We would like to do Save for Later and then budget check before we do Save and Submit. When clicking the 'Save For Later' button, message is returned "Save For Later cannot be performed because one or more lines