When you load audit data from external media, or delete one or more Sites, Network Inventory places audit snapshots for computers, Chromebooks and devices with no associated Sites into the Lost and Found container. If Network Inventory re-discovers a previously lost Network Node in any Site, it moves the respective node from Lost and Found and associates it with the new Site.
Network Inventory does not display the Lost and Found container when it is empty. When there is at least one lost node, Lost and Found appears in the Sidebar below your Sites.