1. Double check the card is definitely out of balance by running an Aged Receivables Detail or Summary dated 31/12/9999 and check if there is no out of balance (OOB) in the report for that card.
If there is OOB in the report as well, it means you will need to check the transactions which caused OOB like if there are any duplicates or incorrect ones.
2. On the card drill into the arrow next to the balance on the card and see if there are any open transactions that equal the card balance, If Yes, then the card is not OOB and you will need to close the open transactions by applying payment.
3. Sometimes, some incorrect credit notes added to the card can cause this issue too so check if there are any credit notes added incorrectly and closed instead of reversing the actual invoices.
Once you have confirmed all the above scenarios and still the card is out of balance then please send us your product serial number and screenshots from the first 2 steps by Private Message so we can escalate it for repair.