When a firewall is not connected to the Firewall Management, its status appears as Offline and Out of Sync on the Manager View | Home > Firewalls > Inventory page. However:
The firewall's static data will be displayed in the Firewall View, and the dynamic pages will be notified as NSM can’t load this page as the firewall is offline.
The last known dynamic IP address (DHCP/PPPoE IP) of the firewall is shown on the Firewall View | Network > System > Interfaces > Interface Settings tab.
This is applicable for Gen 7 and Gen 8 firewalls.