When viewing Container Volumes for a cluster you see that the Health Status field for all of them is Degraded. Selecting the Degraded link brings up a Volume accessibility window that shows all hosts have an Accessibility Status of Accessible with a green checkmark.
vSphere Kubernetes Service 8
One or more of the hosts within the cluster is in maintenance mode.
Once all hosts in the cluster are taken out of maintenance mode the Health Status should return to Accessible with a green checkmark. This is expected behavior.