Upon examination of the controller.log we noticed this error:
"Controller: Can not start cdm, start after probe not enabled (cluster)"
To alleviate this issue we enabled the cluster probe since it had been deactivated during the past/most recent NMS upgrade. Then the cdm probe started right up.
Alternatively we could have removed the 'start_after' entry for the cdm probe in the controller.cfg and restarted the robot, then started the cdm probe.