We found a E-R-A "When note with attachment(s) is edited in Service Catalog request". This implies that you can attach files on notes? We are not aware of this.
This appears to be a 'textual' issue.
The message being send reads: "A Note is edited in the request $request_name$ ($source_id$)".
So, this concerns ONLY a note being processed and is not related to an attachment being included in a note.
Which appears impossible, by the way.