How do you know the tax return was not processed if they took your payment? What are you basing that assumption on? What do you expect to see that would show you if they processed a return with a payment due besides taking your payment? By e-filing after mailing the return with a payment you may just be causing a lot of confusion.
So after being on hold for an hour and speaking with the IRS, they informed me that they can't hold onto a person's payment so it has to be cashed right away. So that is not uncommon for them to process the payment before the taxes. When I log onto the IRS, it tells me that they processed by payment but not my tax return.