Any current advice for getting an exit row seat from NH for NRT-BKK-NRT as part of a UA ticket with NH flight numbers: 8xx?

Previously one could choose the exit row on the NH website using the NH PNR if NH flight numbers, or if UA codeshare flight numbers, the NH/USA call center would grudgingly (Supervisor) give you the seat.

None of these workarounds appear to work now, seats are blocked (show as available for a higher class economy phantom booking).