The NV MC has the option to resync with a poller via a right click on the Poller at the Group tab. This helps to ensure the configuration changes made at the MC and the device changes at the Poller are in sync with each other. However sometimes the 'Resync' option is greyed out. To clear that condition close the MC Console and from a command window run 'nvrestart'. Wait a couple minutes and then open the Console and now it should now be available.