kuofrumdnj

Thanks for this suggestion, you are a genius. IT WORKED!!!!! I will detail what I did below, perhaps this may help others.

To answer your initial question, I've been filling out everything, my wife & my name, our ticket number, frequent flier (i put in our UA's), EVA's confirmation #...etc. Essentially all that can be filled out, I filled them in.

After reading your comment, I went back to my browser and deleted everything that is Optional, essentially only leaving our names, departing & arriving airport, date, airline, and flight number. Usually, before I click submit, I would open United on another tab to sign in, as the website auto-logs me out after a few minutes. This time, I forgot to do that and after submitting, I actually was able to proceed to the next step where it shows that indeed there is upgrade availability! I was too excited at this point, as I've been trying for a few days without success, so I went ahead and click confirm, without remembering to log back in, and of course on the next screen, the website prompts me to log in. After doing so, it went back to the blank SAUA form. So no go yet! I was able to replicate this by "manually" signing out in another tab after initially signing in & completing the form. But in the end, even when I do sign back in before I click confirm, the page always take me back to the blank SAUA page.

What finally worked, for whatever reason, is entering my EVA FF information (I've been putting in my UA's before) while leaving everything else bare minimum. That worked immediately and I was able to confirm this on EVA's website and select our seats.

Thanks again for the huge help and inspiration!