Hi KTServices ,
Apologies for any inconvenience caused.
Are you using the "Add to PO" modal from Stock Central or the Edit PO page? Only the second one will filter by a supplier, but please note that you must assign the supplier and save the order before opening the 'Add to PO' modal.
FYI, we've checked to open the modal from a PO with a supplier assigned using the last PO Pro version. It has worked correctly.
Best Regards,
José Andrés