Performance metrics are not being shown for virtual servers.
OnApp 5.2.x (and later) with VMware Cloud Director integration
1. Go to the VCD instance that you have added within OnApp: log in to your Control Panel > Settings > Compute Resources > label of VCD instance.
2. Click Tools and then vCenter Passwords.
3. Ensure that all of the fields are correct, in order to connect to all of your vCenter's within your entire VMware Cloud Director environment.
4. Once the green mark is shown for each Center server, performance metrics will be shown for all virtual machines.
The incorrect vCenter credentials are the reason, why the performance metrics are not being shown for virtual servers in the OnApp interface.