I managed to get MCY-SYD-DFW, in J in late June, as an award through AAdvantage. I am based in Melbourne, but MCY turned up on a search for BNE departure. I tried MEL, ADL, CBR as origins but they didn't work, nor did a SYD departure with no domestic flight. The same itinerary was available through QFF, but much higher in both points and copay.
Now it all looks to be confirmed in both AA and QF apps. On QF, both website and app, I can choose a seat on the domestic A220. But it won't allow seat selection on the A380 SYD-DFW (only aisle/window preference). I checked ExpertFlyer and the J cabin has tons of available seats. Why would I not be able to select a seat? Will a phone agent do so? If so, what number should I call?