Root Cause: The monitor and the object definition of a Schedule does not show the object types of its tasks. This happened when the Schedule with its tasks have been exported and imported again. The missing object types lead to corrupt context menus.
Update to a fixed version listed below or a newer version if available.
Fix Status: Released
Automation Engine 12.0.0 - Available
Automation Engine 11.2.2 - Available
Automation Engine 11.1.4 - Available
Delete the tasks from the schedule and add them again.