For iOS, Uncategorized Exit (UE) session outcomes, it's possible that a "Last View" could be categorized as "Unavailable".
The name of the view could be unavailable because the session ended before the app had a chance to report it, or because it was reported in a previous session.
For example: If a user clicks on the app icon to open the app and the app does not respond, it's likely that the user experienced an uncategorized exit-related issue upon arrival and the user's last view would be categorized as "Unavailable".