I've also been seeing inconsistent results with the "Account Summary" section (includes balance forward, other credits/payments, other invoices, new charges, and total amount due figures) appearing on generated invoices. It's just as RickH2 said - Sometimes the account summary section is there and other times it's not. It's especially confusing because the template editor web interface clearly shows the mock account summary section both in the Design and Content tabs and if I generate a "Preview PDF" it too has the mock account summary section. But when I print or send an actual invoice, there are times when the PDF has no such section. Another wrinkle with this is that when the account summary section goes missing, the payment request email only asks for the latest invoice amount, not the entire open balance on the account! So again, as OP mentioned, customers have no current indication that they owe anything other than the latest invoiced amount.
