The correct NetBackup master server does not show up for selection for a given vCenter server on the Instant recovery wizard
The vCenter server host name (the FQDN or the short name) should be the same at the following locations:
The name that is registered with the NetBackup master server.
The name that is registered with the vSphere Client (HTML5).
The name that is registered with the plug-in during the plug-in installation.