Japan Airlines blocking Premium Economy ex-SYD

[MissingScurrah]

I've noticed something odd, and I'm wondering if anyone with a better understanding of airline ticketing practices might be able to explain what's going on here.

JAL has scheduled flights from SYD-HND for its Boeing 777-300ERs a bit later in the year, and I believe this has been in their future flight schedule for some months now.

These aircraft are fitted with a 40-seat Premium Economy cabin, yet if you try to book Premium Economy on this route JAL tells you it can't find anything.

Search on their website and it will simply suggest you buy tickets in another cabin, search on a third party like Google Flights and it will tell you that Premium Economy is not available.

However, these flights are definitely Premium Economy equipped - see here a seat map from the JAL booking page of these flights which displays the cabin.

I can't figure out why they'd be scheduling a route with an aircraft type that offers 40 seats in a certain cabin and then blocking that cabin from sale. Any insights warmly welcome.

 

[Beer_budget]

When later in the year? They filed a preliminary aircraft change on this route to the 787-9 which has fewer PE seats: JAL NW26 Preliminary Sydney Aircraft Changes — AeroRoutes

I've seen a few folks on Facebook complaining about being downgraded to whY, so cabin may be fully booked?

 

[MissingScurrah]

When later in the year? They filed a preliminary aircraft change on this route to the 787-9 which has fewer PE seats: JAL NW26 Preliminary Sydney Aircraft Changes — AeroRoutes

I've seen a few folks on Facebook complaining about being downgraded to whY, so cabin may be fully booked?

These dates are just examples (30 May outbound, 6 Jun inbound) but this is not at all isolated to these dates. The cabin is unbookable on every date that JAL has rostered this aircraft type on between March 29 and October 24. The switch to a 2 cabin 787-8 is currently showing only from October 25. I wonder if this means they are planning to pull a swap to that aircraft type from March 29. I guess that would explain why they're blocking the cabin, but odd because these dates have been unbookable for weeks in W and the aircraft type hasn't changed.