I don't understand how, if you create an invoice manually (via the Invoices tab), add in project information, and send the invoice to the client, it fails to appear in the Invoice History section. Only if the invoice is created from the Project dashboard section will the invoice appear in Invoice History. And further, it is only possible to create an invoice in this way if there are unbilled expenses or hours logged for a project.

If it is possible to create an invoice by more than one method, then any invoice created that is associated with a project should be shown in the Invoice History tab. The fact that one can have invoices for a project that do not appear in the invoice history is a major shortcoming of the software. I would recommend finding a solution to this bug immediately. 

Thank you.