LUNs not deleted after PV deleted in ICP 3.2.1

[dannert]

I have created a new storage class as follows:
kubectl describe storageclass ssd-retain
Name: ssd-retain
IsDefaultClass: No
Annotations:
Provisioner: ibm/powervc-k8s-volume-provisioner
Parameters: fsType=xfs,type=icp-v7k3-ssd
AllowVolumeExpansion: True
MountOptions:
ReclaimPolicy: Retain
VolumeBindingMode: Immediate
Events:

I then deployed a mongodb-dev Helm chart with that storage class, tested it and then deleted the deployment. As the storage class is set to Retain the PV was not automatically deleted.
I manually deleted the PV within ICP GUI and ICP has no knowledge of that PV any longer.

The problem is that the Flex driver does not delete the underlying LUN at the time of manual delete of the PV. PowerVC did not receive a "delete" message.

It is my understanding that "Retain" should just keep the PV when the PVC is deleted, but if the PV is deleted that the underlying storage should be release as well.
So that would be my expectation of a correct behavior here as well.