CMK Credit Note - Inbound. purchase order not found when it has NA

Summary:

Via CMK we've received for the 1st time via a service provider, AP "Credit Note - Inbound" messages and we are getting error message "purchase order not found" for all the records, even though it has PEPPOL standard value of NA, or sometimes -.

have logged an SR asking the same.

is there any way to clear out the po_number field within CMK (as not yet got to AP invoice interface tables) WITHOUT going back to the supplier, e.g. with API

Content (please ensure you mask any confidential information):

<cac:OrderReference>

    <cbc:ID>NA</cbc:ID>

</cac:OrderReference>