If a portal user creates a ticket from a website helpdesk form, and attaches a file to it, the helpdesk.ticket is created together with a message. This message has de description "Attached files:", and contains the attachment. 

But, when this portal user later access to ticket in website,  this first message is never shown in the website chatter. The user can create new messages, and attach files to them and they are visible, but not the original one.

Do you know why this first message and its attachment isn't shown to the user?