Might it also be a similar result to what I found when searching BNE to LHR one time. On BA metal, normally BNE to LHR is QF domestic to SYD and then BA16 via SIN. On the occasion I got a message saying the A380 was available on that route, it was suggesting a QF or CX flight to HKG and then BA25 from HKG to LHR.