(My 1st post here. Be gentle)
According to the United Fleet website, all thirteen 78Xs have Polaris and PE.
789 tail N35953 is scheduled LAX-SYD-NRT on the 13th returning NRT-SFO on the 14th, but neither N27957 nor N24972 are scheduled to leave XMN yet.
789 tail N13954 that has been stuck in Frankfurt is at this writing scheduled for FRA-SFO in 2 1/2 hours. Is it conceivable they've been waiting for this plane to come back on line?