Net income will not be matched in your open invoice and also for your bank because the bank account transactions do not only affect income and expense, it will also affect the liability and asset accounts.
Also, you'll need to consider the accounting method on your Profit and Loss report which is the Cash or Accruals. Combining your bank account and open invoices means you're reporting both Cash and Accrual as one. While Profit and Loss will only allow you to report either Cash or Accrual only.
You can follow these steps on how to change the accounting method on a report. Here's how:
Go to the Reports tab.
Choose a report.
Select either Cash or Accrual in the Accounting method field.