I've been a FitBit Charge user since the 3 and used to have a Visa card working in FitBit Pay on my Charge 5. At some point I noticed the card was gone but I am totally unable to add that same card – or any other – to my wallet. I can add the card, accept the issuer's T&C, etc. but when it tries to verify the card I get the error message "An unexpected error occurred. Please try again later."
To be clear, the same card used to work fine, so I know it's a bank (Chase) that works with FitBit Pay, and I just reviewed the bank list and confirmed it shows "Chase Bank (Visa)", and as mentioned above, it shows me the Chase terms & conditions page, so it clearly should work, but it never does. I've tried multiple times over the past several weeks so I know it's not just a momentary hiccup. I've tried other cards, and they all produce the same error.
A few months ago I noticed that the FitBit iOS app started freezing up around 90% of the time when launching it, so I deleted and reinstalled. I almost never use FitBit Pay so I have no idea if the problem started right after that or not, so maybe it's related, maybe not, but just now I tried signing out and back in, deleting and reinstalling, and every other permutation of ways to get a fresh start, but still no luck. In case it's relevant, I have not yet converted my FitBit account over to Google. I hope they aren't deliberately breaking stuff that depends on the old accounts to get people to switch over but I wouldn't put it past them.
Anyway, if anyone has run into this problem and successfully gotten past it, please let me know!
