Need help with Invoice Media default - trying to email invoices as attachment

We are trying to use the Invoice email as Attachment feature in PSFS 9.1.   When we set up a contact ID and associate it to a customer, and under documentation have the INVC be "Email Invoice as Attachment", and then create an invoice within PeopleSoft through Standard Billing.   The Invoice Media automatically defaults to "Email Invoice as Attachment".   When we complete the invoice process the invoice is emailed as expected.  When we create an invoice within PS through Standard Billing that does not have a Contact ID set up or associated to a customer, the Invoice Media defaults to "Print