please bear with a inexperienced OZ flyer / expertflyer user.

I'm trying to see what availability is for an upgrade to first (O) on OZ for JFK-ICN, but when i search for award inventory JFK-ICN, no direct flights show up, only a connection through NRT with the long-haul leg on NH and the NRT-ICN on OZ. I saw on an earlier post someone mention that OZ does not make upgrade availability known to expertflyer, but if that were the case then its unclear to me why it shows up on the NRT connection. Am i missing something? And if OZ does not release its O/I inventory, how do people track when inventory opens up? (or is the only option to check on the ANA website daily).

thanks in advance.

addendum: i tried spot checking random dates and it seems like the direct flight shows up on some dates but not others. would appreciate anyone's take on this.