Upon creating a new expense report from an employee record (Related Records > Transaction subtab), select the Cost Category and mark the expense as Billable on the line items.
When checking the GL Impact, it still shows the account set in the Cost Category instead of Track Billable Expense in field. This is because the account on Track Billable Expenses in field get entered only when the expense report gets invoiced, not when the expense report is created.
To test, proceed to create an invoice on Transactions > Sales > Create Invoices:
1. Under Billable Expense, select the expense.
2. Save the Invoice
3. Navigate to Actions > GL Impact.
3. GL impact shows account set as Track Billable Expense in the cost category account.