Found another bug in case someone is tracking these from or on behalf of UA.
Booked a coach one-way yesterday TPA-EWR ($99 in Y vs $1,479 in F), applied +points. I previously posted about an error I got with the +points search, with picking E+ seats as 1k.
Today, I checked the website for any buy-up offer and it was $199, so I took it obviously since this route is almost ALWAYS full in first. I checked out with my purchase and click the "select my seats" button. My old E+ seat is still shown and when I pick a seat in F and "save", it sends me to a check-out page to pay the $199 again. I already got my receipt via email from the purchase so I close the window, go back to the home page, click "my trips" and go to the itinerary. Seat 1A was auto chosen for me, so I click that and it takes me again to the seat map where I move it to what I want, and it saves without issue.
It's truly crazy how many things have gone wrong with this "upgrade".... I'm sure UA will sort it out -- I think their site and app is/was excellent. But, wow...