How to reproduce:
select a PO that has the maximum number of POLs already
Click add POL
When popup appears click "Create new purchase order"
add required details to POL and click "Create PO Line"
Actual: see error toast message that line could not be saved.
Expected: line details are saved and creation screen is dismissed.
Note: if you cancel line creation and start again adding the exact same details to the POL it will save successfully