PR created instead of PO - only some Vendors?

Hi in classic scenario Purchase Reqs are being created instead of Purchase Orders in the backend. I have found that by transfering the Vendors across again via BBPGETVD this normally fixes the problem even though the Vendors already appear to exist in EBP which is strange???. However I now have a situation with some vendors where PR's are still being created despite the fact that I have re-transfered the Vendor across.

I can create a cart for some Vendors and a PO is created however with a different Vendor a req is being created - please can someone advise what on earth is going on ?

Kindest Regards

Paul