Well I think I found the problem, though I’m not sure why it occurs or what ‘rule’ it breaks.

If my first flight is not on Qantas or Jetstar it won’t let me do the CHC to YVR flight.

If I go from TYO to an Australian airport, I can do the CHC-YVR flight.

If I originate in BKK (instead of TYO) and go to SIN on Jetstar (3K) on my first flight, I can later do the CHC-YVR. However, if I change the BKK-SIN flight to the recently reinstated CX one then the later CHC-YVR has to go via AKL and HKG.

So start on QF (or one of the Jetstars) then all good, anything else then it’s no no no!!

Perhaps this is something that a travel agent could overcome, but don’t think I can.