Problem
You are unable to issue a refund on an invoice due to an error message.
Solution
Go to the Pricebook in ServiceTitan.
Check if the refund task is marked as Taxable.
If the refund task is marked as taxable, clear the Taxable box.
Save the changes on the task.
Issue the refund.
Note: If the invoice is already posted, the refund task may need to be re-added in order for the changes to take effect.