From the Commission Detail Page, scroll down to the "Agent Open Balances" section. The Invoice Balance column refers to open invoices on the front-end of the system (LSS). The Accounting AR Balance refers to the balance in QBO. The Accounting AR Balance includes the Invoice Balance amount since invoices in the front-end of the system sync over to the Accounting side. If the Agent only has a balance in the Accounting column, then the open invoices were created in the Accounting module, such as those tied to Billable Expense Charges.