I've just made WP for the first time ever (30 years into my relationship with QF) and thought I would give this a go...
I requested 2 U or 2 Z seats on QF11 SYD-LAX for 3rd July 2025.
Expert Flyer was showing decent inventory for this flight
F9 A7 J9 C9 D9 I9 W9 R9 T9 Y9 B9 H9 K9 M9 L9 V9 S9 N9 Q9 O8 X0 E0
Computer said No to Business (despite the I9) but it did release 2 x Premium Economy seats (with T9) to me. I *think* that I may have got through to HBA on my first attempt as WP (gasp!) ... I had an English chap on the other end of the line, who knew exactly what he was doing, was able to transform my existing CR booking from 2 X seats to 2 Z seats, deducted the extra QFF points (including change fee), and confirmed and ticketed the new Z class CR booking within 10 minutes of me calling.
If only it was always so easy