Matt,
It is possible that you use the discontinued version of the mobile app.
Please uninstall the old app then visit the app store and download the most current version. In the initial screen select “existing account” and login with your current credentials.
Let me know if this doesn’t resolve the issue.
After a few rounds of resetting and reconnecting, it is working again now. From the messages I was getting it really looks like a problem on the server side, i.e., my login wasn’t being recognized. I didn’t change anything and the problem seemed to get resolved, so I can only assume that the server issue was fixed.