The Archived Vendor Copy does not save in the Attachments\PO folder. It saves in the SoftPDF folder so that the AP Vendor transaction record can have a PDF viewer button. Are you trying to email the PO to the client? If so, you need to use the Email Button in the PO print dialogue box. You don't need anything in the Attachments folder unless you want to attach additional documents.

Either printing or emailing will store the PDF for later viewing.