Symptoms:
• VMware vCenter Server Appliance 7.0 Update 2 
• Unable to see permissions for ESXi hosts that are in clusters
• Permissions are visible for ESXi hosts that are NOT in clusters (under the datacenter object level, outside of a cluster)

VMware vCenter Server 7.0.x

This is a known issue with vCenter Server 7.0 Update 2, Update 2a and Update 2b

Workaround:
To manage permissions for ESXi hosts in vCenter Server that are in cluster(s):
A. Use PowerCLI: https://blogs.vmware.com/PowerCLI/2010/11/managing-vsphere-permissions-with-powercli.html
B. Move the host out of the cluster object, make necessary changes, and then move the host back into the cluster

Note - when moving hosts in and out of clusters, they must either be in maintenance mode or disconnected. Connected ESXi hosts with powered on VMs cannot be taken out of a cluster.