Problem

The original filenames attribute is not persistent and couldn't be shown in Message Tracker.

Resolution

This type of issue might be sporadic and it might occur periodically based on the specific type of file sent and encryption method choose by the partner.

AS2 module uses https://datatracker.ietf.org/doc/html/rfc8551 for data encryption
Filenames are sensitive data and must be inside the encrypted content.
When it worked - the header was in the proper place - encrypted. When there is
Content-Type: application/pkcs7-mime; name="smime.p7m"; smime-type=enveloped-data
Any sensitive data is looked up only in the encrypted data. Sensitive data in plain text headers is ignored.