Here are the symptoms:
- "DRS invocation not completed" error
- Some of the hosts resources do not show up in the cluster view
In order to resolve this issue, console into the hosts that do not show any CPU/memory resources. Once logged in, go to Troubleshooting Options > Restart Management agents, then go back to the vSphere client and right click the host and select Reconfigure for vSphere HA. After applying these steps to all affected hosts, re-run DRS and the issue should be resolved.