(2022 Extension) E-file Transmission Failure: A return with the same SSN or EIN has previously been submitted.

I received this error message when trying to file a 2022 Extension.

E-file Transmission Failure: A return with the same SSN or EIN has previously been submitted.

I called customer support and left hoping that clearing critical errors would help process the extension. Unfortunately, that did not work. Since it was already rejected, I copied it and made sure to clear the errors again; same message. Then I thought it was maybe the IP PIN but that's not working either. Both the original and the copy have grayed out SSN for the taxpayer, not the spouse. I've double checked the SSN and it is correct. I don't want to make another copy as it takes up my credits.

The only other time this happened, a return had been filed by their former preparer and they hadn't realized it. My client says that they've made no extension requests to another preparer for this year.

I really hope someone can respond. Please and thank you!