Supplier Attachment Displays at BWC but not the PO Form

Hello,

We noticed that for a Supplier with a Misc Attachment, the Supplier Attachment does show up at the Buyer Work Center when creating a PO for this Supplier. And I can open the Attachment to view the content. But when I search this same PO at the Standard PO Enter Form, the Attachment icon looks like that there is Attachment. But once I clicked the Attachment icon, inside is empty.

Is this difference behave between BWC and traditional PO Form normal?  I did some quick search on Metalink/Oracle Support and did not find anything.

Thanks.

Wonly