If a vCenter compute cluster is DRS-enabled, the cloud zone only displays the cluster in the list of computes and it does not display the child hosts.
If a vCenter compute cluster is not DRS-enabled, the cloud zone only displays standalone ESXi hosts.
Resolution
For the vRA cloud zone to recognize compute clusters, we need to enable DRS on the vCenter Compute cluster.
Steps to enable DRS on vCenter:
1. Browse to the cluster in the vSphere Client. 2. Click Configure. 3. Under Services, select vSphere DRS and click Edit. 4. Select the Turn ON vSphere DRS check boxes. 5. Click OK.
vRA cloud zone does not recognize a cluster object unless DRS is configured on vCenter Compute Cluster otherwise will only recognize standalone ESXi hosts.