MA540 Vendor Payment Terms v. AP10 Vendor Payment Terms

Has anyone else run across this? We use GHX for our MA540 files. On one specific vendor, the payment terms coming in through MA540 (payment terms are N30) are over-riding the Vendor Terms set up in AP10 for that specific vendor (N1). We need to pay this vendor at N1. We manually have to go change the date on each invoice or all of the invoices pay late.

I can ask the vendor to change the terms on our account to N1, but this doesn't solve the root problem. Why is the MA540 file data over-riding our AP10 info? For all of our other vendors, the AP10 vendor payment terms over-ride the MA540 payment terms on the invoices.

This had happened before, and I had heard that this has something to do with a set up somewere in the PO module, but the person that solved the problem is no longer here.

Any ideas?

Thanks.