On the "Manage bounces" pages, you might get a typo if only one mail have bounced.
If this is the case and you press "Parse mails" button (after pressing "Collect all mails") , you'll get the following message:

Mailbox item parse result
1 mails parsed

btw, there is also bit inconsistent the status message you get when pressing "Collect all mails" button:

Collection result for mailbox 1.
    * Added: 1
    * Already exists 0
    * Failed 0

There are missing some colons. It looks better like this:

Collection result for mailbox 1.
    * Added: 1
    * Already exists: 0
    * Failed: 0