I figured I'd wait until after midnight. I tried several browsers, PC's and operating systems and all get the same result (I work in IT so I've done all the troubleshooting on my end that I could)

I think it may be an issue with their systems being overloaded, due to the number of cancellations today. I think I'll wait until after midnight and see if the system volume goes down. Worse case, I'll just plan to get to the airport tomorrow a bit earlier and check in via a kiosk.