Can't add Curve card

Hi folks,

I have a standard Curve X account that I am trying to add to Fitbit Pay in the UK. It just never gets past the Verification stage with the below error. It is NOT a Samsung Pay Curve, but a regular Curve X using the virtual card number (my physical card is in the mail still).

Curve is meant to be supported in the UK on Fitbit Pay, but the app can’t seem to verify it with you?

Does help or support not happen on the Help forums?