Sent items auto archive issue

Hi, I’m having an issue with auto archiving from the sent mail folder on my IMAP mail server. Messages in this folder aren’t being archived to the corresponding folder in the archive - they simply disappear. All the other folders are working just fine in line with the parameters I’ve set up.

Worst of all, they are still disappearing from the sent mail folder as if they have been archived - so I can’t see them to check what I’ve sent, nor search for them.

I’d be grateful for any suggestions as this one has me really stumped.