I am looking at the end of the calendar for a J (or F) award from SYD or MEL to North America, ideally on a JL route on A350 equipment transPac. I am now within a day or two of the optimal departure date becoming available.

In the past a straight (say) SYD-SFO or MEL-DFW search on Cathay, would turn up mixed J/F routings if (say) SYD-HND is available in J but HND-SFO is available only in F. The fare would then be prorated based on the fraction J vs F, which is pretty reasonable.

I am now finding that, even though SYD-HND or MEL-NRT are availabe in J, then HND-SFO or HND-DFW are available the next morning (under 24h) in F, I am not being offered the mixed-cabin result. Is there a hack to forcing this to be available? Or is this something they will construct over the phone if I call them? If phone, what's the best number at ~00:00 HKT? I'm in Australia but if I'm better off calling a HK or US number that's fine.