You should make sure your sitebot is allowed to connected without ssl. This isn't a big issue since it's usually running on localhost.
Code:
Require_Encrypted_Auth = !-sitebot *
Require_Encrypted_Data = !*
Note that you should replace "sitebot" with your sitebot's username and that you might be able to enable ssl fxp with ioFTPD 5.8.6 (which I haven't had time to check yet).