Thank you, @BrandiLO1 for your response. I've tried comparing my old PC's Documents\TurboTax folder to my new PC's Documents\TurboTax folder. They are quite different, which has me concerned.
Then I decided to just look for all files ending in *.tax2020, which I presume is last year's return. I can't find any file with that extension, on either machine.
Then I went to my OneDrive account and searched there. I couldn't find it there, either. However, I was able to find a file with an extension of *.tax2019.
What do you (or anyone else) suggest at this point?
