Why did AutoInvoice reject transactions?

During AutoInvoice processing, if you have transaction lines that fail validation, the import process looks at the value of the Invalid Line field in the transaction source to determine what to do about the transaction.

If the value is Reject Invoice, then AutoInvoice rejects all of the transaction lines that make up one invoice according to the grouping rule, if any one of the transaction lines are invalid. For example, if a grouping rule specifies that three transaction lines should be created as one invoice and one of the transaction lines has an error, AutoInvoice rejects all three transaction lines and doesn't create an invoice.

However, if the value is Create Invoice, AutoInvoice rejects the one invalid transaction line and creates an invoice from the two remaining valid transaction lines.