The NPM virtualization summary or VM node details are not showing any data on VMan resources and displays the following message:
Data Not Available
This can occur when VMan is unable to resolve the hostname to IP address of the Orion server making VMan unable to send data to the Orion server.
Warning: Create a back up or take a snapshot of the appliance before making any changes, in case you need to roll back later.
Check VMAN logs to make sure information is being sent to the Orion server without error. Also make sure its trying to send to correct IP/Hostname of the Orion server via the logs.
You can view VMan logs from the VMAN webconsole:
Under the Solarwinds Mgmt Tab there is a button that says "View Recent Log Activity" where you can view the logs.
More logs can be found via "Bundle Logs" button at the bottom of the Solarwinds Mgmt Tab which will zip all the logs up for you to view.