While the general resolution steps for a Business Validation Error typically resolve all issues, some errors are even more specific and may require additional steps.
For this particular Business validation error, it generally occurs when a transaction was entered as $0.00.
Check the invoice in question to see if you have a payment recorded as $0.00 like the image below.
If you do, you can go ahead and select the edit icon beside the payment and delete it. Your invoice should sync afterwards.
If you still encounter any issues after making the necessary adjustments, please contact us via the Chat Bubble in the bottom right for further assistance.