Adding money from your Eligible American Express Card will be immediate.
However, some users will need to call American Express if they encounter the "Sorry, we are unable to process your payment. Please call the number on the back of your American Express Card to resolve this issue." error message.
We cannot resolve that issue on our end, as American Express authorizes the charges and we cannot process charges that are not authorized by American Express.
Note: All American Express Cards will go through a review process before they can be used to add funds in the Abra app. This review can take up to 24 hours to complete (excluding weekends and holidays). Some users may have to submit additional documents for verification.