My latest go at this has driven me crazy. Was booked on LAX-HND-LAX, which got canceled and auto rebooked onto LAX-SFO-HND (four hours earlier departure and nonstop became one-stop) and NRT-LAX (1.5 hours earlier departure and different departing airport). Those new flights did not work for my schedule, so I called to get rebooked onto LAX-NRT-LAX on different dates within the +/- 7 day window that UA's schedule change policy permits.

1. First agent knows what to do and goes to her supervisor to force the upgrade through, but the supervisor declines. I have a brief chat with the supervisor, gently forcing the issue ("I've had upgrades preserved after rebooking due to schedule change dozens of times in the past") but she wouldn't budge. I hang up and leave the flights as is.
2. Second agent immediately books the new flights into coach and goes off to "manually request" the upgrades. Turns out she only moved the waitlist over, so I ask her to get the upgrades confirmed in line with past practice and policy. She puts me on hold but the call gets disconnected.
3. Third agent repeats the same nonsense the supervisor told me on call #1 (I'm pretty sure the supervisor left notes). Something to the effect of: "the upgrade can be preserved if you're traveling on the same day within 2 hours of the original flight, but not if you're changing dates, as there are other 1Ks on the waitlist." I again try to press the issue but it goes nowhere, so I thank her and hang up.
4. Fourth agent was willing to listen and try to help. She made several trips back and forth to her supervisor, but this new supervisor still won't budge.

These calls have taken 3.5 hours in total, and I still don't have a satisfactory outcome.

Have I just been unlucky, or what on earth has happened? I'm usually able to use most or all of my PlusPoints at booking every year, and decided to stretch for 1K requalification next year on this basis. But if UA is going to make the process of cleaning up their own schedule changes so agonizing (on top of continuously dwindling confirmed availability at booking), then there's little in it for me next year and beyond.