Delete attachement not workin

Question

I'm using licensed version to clean attachments from IMAP account with outlook 2016.

All seems to work but it's not working. The attachments disappears from the emails on the folders but i can see on the real mailbox (i have access to mail server) that the attachment appears on the local email (maildir mailbox format) encoded as usual. The size of the emails also is the same after deleting the attachments.

The real size of the mailbox is the same but from every email (from IMAP outlook perspective) the attachment has dissapeared. For me, it seems like the feature of delete attachements works hiding the files attached, not really deleting from the mailbox.