Just to add my own input to one of the many detailed idiosyncracies in the OP's account:

Me (1P), wife and daughter travel twice a year LAX-OGG-LAX on UA - always on reward tix (no paid fares). As a 1P, I have always been able to select E+ seats for myself and one other for free. (My wife and daughter have no UA status at all - not even a MP number.) I then easily select and pay for an E+ seat for the third pax on our single PNR. We have always been seated together, the seats have stuck, and there have been no problems. Been doing this for at least the last three years.

The only minor glitch in the website is that if I wanted to change my seats from my assigned E+ seats to somewhere else in E+, the site wants to charge me again. But since I never want to change my originally assigned seats, I've never had to bother with this glitch. If I did ever want to change my seats, I would just call in instead.

This post only speaks to the fact that Premier members should be allowed to sit in E+ (obviously) and have one additional non-status companion on the same PNR granted E+ seating. Two Premier members on the same PNR should be allowed two non-status companions (in total) on the same PNR to the same E+ privileges, even on award tix.

Bottom line - This aspect of the conundrum should probably be taken off the table.

If I had to guess (which is risky in this rather convoluted thread), I'm betting that there was a possible equipment swap between 777 configurations that took away row 17 - at least temporarily, throwing the original seating assignments out of whack. Then a return swap back to the original configuration reinstituted row 17, which are now under airport control due to the now impending departure date and time. If this is true, then there still is the outside chance for a happy ending to this situation.

Is there a way to find out whether my theory might be possible? I'm guessing not, since a swap back and forth may not actually be trackable via customer means...