Calling again did indeed work! I asked for exactly the same thing as before, but this time they were able to find the US Airways flight that I wanted. I guess the US site and ANA tool were both accurate, just UA agent missed it.

I'd like to note that when I subsequently called to make changes to the outbound, I got very helpful agents that did not seem like they were from the ICC. The first one even said she was in Chicago, so maybe the trick is to make a reservation (anything) and then call to change it.

I guess it would be most accurate to say that I was disconnected, not hung up on. I was getting frustrated with that agent in that she kept thinking I wanted to use US miles, not look at a US flight, but it certainly wasn't a heated discussion. I was put on hold, with the usual music recording, then the recoding stopped and no one on the other line.

"If you don't get the answer you want, call again." rings true yet again.