Recently have had to deal with PlusPoints deducted for the short legs of multileg trips (ie. EGE-DEN then DEN to SFO that didn't clear and BOS-EWR then EWR to SFO that didn't clear). I know you have to cancel out of the upgrade or lose the points on the short run but it seems like you should be able to do this through the app or online. The other day I was on the phone for nearly 30 mins trying to cancel an upgrade and redeposit the points on the long run. Just a suggestion to UA.
FWIW I probably should start just using them on the short runs as virtually NOTHING has cleared for me this year on anything over an hour. (SFO-DEN-SFO, SMF-ORD-SMF, SMF-EWR-SMF, SMF-DEN-BOS-EWR-SMF, there are others but list is already too long). Pluspoints are pretty worthless as a Plat but I should make 1K by summer, however, given my history I doubt I'll see much improvement. I don't even fool myself into thinking I'll clear a CPU these days.