Thanks moondog. I sent you a PM, but I also decided to do a dummy booking PVG-HKG. That booking indeed brought up the seat map after entering the passenger details. So it looks like a glitch for flights ex TPE (any maybe other outstations?)

Interestingly, when selecting spring plus PVG-HKG it gives you front row VIP free of charge, but wants an extra USD7 for row 2. Wonder what would happen if you didn't pay for seat selection.