I booked a paid J one way to PER for next week and could select any seat in the J cabin that was showing as available.
I also booked the return on points to SYD in J via MEL and could select seats for both legs, so no issues for me when booking either paid or on points.
I also booked the return on points to SYD in J via MEL and could select seats for both legs, so no issues for me when booking either paid or on points.