NH showing availability, but cannot redeem from SQ
I've used AwardNexus and award.flights to find availability for a flight routing from HKG - TAS. Both show the same availability on SQ's Star Alliance partners ANA and Asiana and I've double-confirmed by checking ANA's website (of which I'm also a member) to show that the award is bookable through them:
HKG - NRT on NH
HND - ICN on OZ
ICN - TAS on OZ
That being said, when I call into SQ's call centre and ask for availability, walking them through what I've found, they say 2/3 segments are available, but they have no availability for the last ICN - TAS segment on any class. I mentioned to them that ANA is showing redemption availability for an OZ (Asiana) business class flight and they said that they might have different allocation.
Is this possible within Star Alliance members? Or is it possible that availability hasn't opened up to SQ yet? I thought if availability wasn't open, it would be all or nothing, either all OZ or none. Any tips to secure the booking would be much appreciated!