Sub-accounts must be separated from the parent accounts with a colon when created in ServiceTitan. For the transactions to export successfully, the sub-accounts must be written in the following format "Parent account:Sub account".
For example, if the "Sales Income" account is a sub-account of "Income" parent account in QBO, we need to create the account in the ServiceTitan General Ledger account in the following way "Income:Sales Income."
Additional resources can be found here! If you continue to experience errors, don't hesitate to get in touch with ServiceTitan support.