In which scenario do normal billing errors not display?

Normal billing errors do not display when editing an existing invoice or cash sale. This is because the system is designed to validate and enforce business logic when creating new transactions or when progressing through the sales cycle. When an invoice or cash sale is being edited, the underlying data has already been established and the normal validation checks may be bypassed in order to facilitate quick edits and corrections.

In contrast, scenarios like creating a new invoice from scratch or submitting a sales order involve fresh data entry, where the system actively checks for any inconsistencies or errors. Similarly, when an opportunity is converted to an invoice, a new transaction is being created, invoking all necessary validations. Thus, the process of editing already established invoices allows for a more straightforward approach, which is why errors do not display in that specific scenario.