This problem only occurs if your merchant processor is Paragon. When viewing a client’s transactions on their profile page, the ACH payment type displays the transaction State as Failed. When you hover over the tooltip beside the failed transaction, it says You have already charged this card this amount. Please wait fifteen minutes or change the amount of the transaction if this is not a duplicate payment.
Paragon can only process one ACH payment from the same client account per day. It is recommended that you process each transaction two days apart to avoid errors like this.