You've set up KOFF on an Outlook client that supports AutoArchiving and the account has data that's not being archived when AutoArchiving is run on the entire mailbox.
Only the items inside the Inbox folder are being auto archived.
KOFF syncs the INBOX folder in 'full mode', while the other folders are synced in 'header-only' mode. Because of this, Outlook AutoArchiving does not work on other folders - there is no data to move per see, only the headers are synced to KOFF.
To fix this, you need to enable the option to 'Synchronize whole messages' in the Outlook folder settings, for the folders that require to be AutoArchived by Outlook.
It is possible to face issues in some cases when changing the synchronization mode after a folder is already synchronized - some items might be stuck as 'header only'.
It is recommended to do a full re-synchronization (reconnect the KOFF account) after setting the folder synchronization mode at the beginning.
Please note that this operation increases disk space usage and troubleshooting issues related to it is outside of support scope.
It is worth mentioning that archiving features like this usually delete the emails from the Kerio Connect mail server and move them to local email files such as .PST files. These files tend to grow with time and become corrupt or inaccessible in the event of a system crash. It is recommended to Configure Backup in Kerio Connect instead.