Dovecot/Pigeonhole, Leap 15.5

Installed Dovecot23 package via YAST. Dovecot configured and working for some months now. Added Roundcube along the way. Attempting to configure Sieve/Manageseive, found Roundcube could not contact managesieve. Reason being the port, 4190, managesieve is configured to listen on, is not bound. Cannot telnet to it, on the local box, nor does it show via socklist or other port listing means. Does not appear to be a misconfiguration of dovecot. Anyone have such a thing working?