I don't think any of the answers here are correct... I think this is a bug.
The poster is describing the same issue I am having. I uploaded form 1099-B during the interview process, and TurboTax said it would send the PDF 1099-B to the IRS for me so I didn't have to mail anything in. Yet, the filing instructions ask me to send in Form 8453 with the 1099-B, even though the pre-populated Form 8453 is not generated by TurboTax (as it has done in years past when I actually did have to mail it in).
For clarity, here is the message that TurboTax provides during the interview process on the 1099 page:
"Now we'll help you upload your 1099-B since the IRS requires a copy
The IRS requires a copy of your 1099-B because you need to provide documentation for some of the transactions on your sales summary.
If you have a PDF copy, upload it and we'll send it to the IRS for you.
If you don't have a PDF copy, you can skip upload and we'll help you mail a paper copy."
As instructed, I have uploaded a PDF copy, so TT should be sending this to the IRS electronically and should NOT be asking me to mail a paper copy.
