Hi Jackson,

Thanks for the additional information. Did you issue any refund for this customer? If yes, you can create an expense transaction to offset the adjustment note and then, link them together using a receive payment option. 

1. Click on the + New option and select Expense.
2. In the Payee select the customer name.
3. In the Payment account select the bank the money was refunded from.
4. In the Category use Accounts Payable.
5. Enter the amount of the refund.
6. Select the GST code.
7. Click on Save.
8. Next, click on + New and choose Receive Payment.
9. Select the customer name and payment  method.
10. Balance should 0 out.
11. Click on Save and close.

Check the customer transaction list to see if the balance 0 out. If the issue persists, I recommend contacting directly our Customer Care Team through the Help panel and click on Contact Us through Chat or Phone. That way, one of our support agents can check the transaction to better help you.

Feel free to post again in the Community if you have other questions.