In Automtation Engine 11.2.3, when you add a UserDefined Metadata in a Schedule object (JSCH), it keeps activating/starting every 20 seconds after the period turnaround time.
The screen shot below shows the client has been stopped to stop JSCH from activating every 20 seconds.
To stop the activated JSCH from activating every 20 seconds, the Client must be stopped, then deactivate JSCH.
1) Upgrade Automation Engine to 11.2.4
2) Don't use UserDefined Metadata in JSCH in Automation Engine 11.2.3
Note: This behavior does not exist in 11.2.4 or 12