When the `controlplanemachineset/cluster` object is manually deleted, the `control-plane-machine-set` Cluster Operator (CO) does not change its state to Degraded or Progressing. The operator continues to report `AVAILABLE=True`, `PROGRESSING=False`, and `DEGRADED=False`.

This behavior is unexpected, as the absence of a critical resource like the ControlPlaneMachineSet should be reflected in the operator's status, alerting administrators to a potential problem.

A possible cause for this issue may be a misconfiguration in the Cluster Operator's `relatedObjects` definition. 

The entry for `controlplanemachinesets` has a blank `name` field, which might prevent the operator from correctly monitoring the state of the `cluster` object.

$ oc get co control-plane-machine-set
relatedObjects:
- group: machine.openshift.io
  name: ""
  resource: controlplanemachinesets 

    4.19.2, AWS, IPI

    100%

1.  Identify and verify the existence of the controlplanemachineset/cluster object:     

$ oc get controlplanemachinesets.machine.openshift.io cluster -n openshift-machine-api

NAME      DESIRED   CURRENT   READY   UPDATED   UNAVAILABLE   STATE      AGE
cluster   3         3         3       1                       Active     32m 

2. Delete the `controlplanemachineset/cluster` object: 

$ oc delete controlplanemachinesets.machine.openshift.io cluster -n openshift-machine-api
controlplanemachineset.machine.openshift.io "cluster" deleted

3. Verify that the object has been removed:

$ oc get controlplanemachinesets.machine.openshift.io -n openshift-machine-api
No resources found in openshift-machine-api namespace.

4. Check the status of the `control-plane-machine-set` Cluster Operator:  
$ oc get co control-plane-machine-set

NAME                          VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE   MESSAGE
control-plane-machine-set     4.19.4    True        False         False      68m

 The `control-plane-machine-set` Cluster Operator remains in a healthy state, showing no signs of degradation or progression.

NAME                          VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE   MESSAGE
control-plane-machine-set     4.19.4    True        False         False      68m

   

The `control-plane-machine-set` Cluster Operator should enter a Degraded or Progressing state immediately after the `controlplanemachineset/cluster` object is deleted. 

Its status should indicate that the required resource is missing, for example: 
  * `DEGRADED=True`
  * `PROGRESSING=True`
  * A message similar to: `ControlPlaneMachineSet "cluster" not found`