Connection Center Does Not Forward Alerts with TicketId to Cherwell
You have an alert with an existing TicketId in SCOM. The conditions on the alert change so that this matches the Cherwell subscription criteria. The alert is not raised as an Incident in Cherwell.
The TicketId field in SCOM is used by Cherwell to store a key as there is no other appropriate location for this data. Because of this Connection Center will attempt to update the incident currently in that TicketId field. In the event of a non-Cherwell Incident ID, this will fail.
Removing the existing Ticket Id will allow Connection Center to treat this as a fresh alert (as long as the conditions still match) and raise this as an Incident in Cherwell.