Thanks, GunOfNavarone. I just called AA again and it turns out my 1 hour 45 minute layover in SFO falls 15 minutes short of the 2 hours minimum (who knew), so the system was preventing it from ticketing. Luckily there was a seat on the HKG-LAX flight, so I switched to that instead. The reservation just ticketed in under 10 minutes.

Is there a good reason not to try and switch to the direct HKG-ORD flight if it opens up? Considering my current flight LAX routing leaves HKG around 1p, and the ORD flight leaves around 2p, I'm guessing the service is basically the same. I was originally excited to get dinner and maybe take a shower for fun at the Wing in HKG, but in reality sleeping in my own bed a night earlier is probably worth a lot more than that, right?