I found a workaround which allowed me to add my failing Chase Cards:
- Go through the process to try to add a card - When you see the failed to add screen stop, don't dismiss the popup.
- Lock the phone and wait at least 15 minutes (trying sooner doesn't work, don't dismiss the popup)
- Unlock the phone
- Tap "Try Again" (dismisses the popup) and immediately hit "Next" in the top right. This time, it will work.
I have a theory that this is some sort of rate limiting at play. There's a bug on the add card screen that causes that very first screen (the one where you pick between adding a credit card, transit card of ID) to blow through a rate limit server-side. From then on, you're doomed to fail if your card add requires one of the URLs that's been rate limited. Once you've entered all your card details though, there's no more hits on that URL that's rate limited happening in the background (which is why I think it's a bug on that first add card screen). Thus, waiting 15 minutes allows the rate limit to clear and the card add to be successful on the next submit attempt.