AMEX, Chase Debit and Chase Slate all working ok for me. Capital One can be added but not verified using the app because the verify button isn't tappable in iOS 10 - I'll call them and verify it that way at some point.
I'm having the same issue with a Halifax card. Annoyingly I'm sure I set it up during the intial phone set up, received the auth code but it doesn't seem to have kept it. I'll try calling them when I can be bothered