I eFiled my taxes, but still received IRS notice CP59/form 15103 for 2019

Last year, I e-filed my 2019 taxes using the desktop (downloaded) version of TurboTax Premier.  I received email confirmation from Turbotax on June 27, 2020, saying that my federal tax return was accepted by the IRS.  However, in March 2021, I received a CP59 from the IRS, saying I had not filed my return.  In order to rectify this, it appears that I need to submit a form 15103, which asks for a "signed and dated" copy of my return.  How can I get this this signed and dated copy of my return?  Inside the TurboTax Premier application, it seems to only have an unsigned/undated .pdf copy of my tax return.

 

Many thanks in advance for your help.