I'm not that surprised.Not exactly a date that most people want to fly, but I did just find one UA J reward seat from BNE to SFO back on the VA website:
When the flight is almost entirely empty, they will prob open to partners:

As I've mentioned in other threads, with US travel weakening, carriers are getting desperate to fill seats.
Qantas has award availability to the US in historically one of the busier travel periods of the year — the week before Christmas:

