what forms do I need to attach to form 8543?

Hi, I'm hoping that someone can help with this question.  Here is the sequence of events:

  1. I e-filed my 2020 federal tax return
  2. Turbotax informed me that I needed to print and mail form 8453 to the IRS even though I filed electronically.
  3. Form 8943 says I only need to file it if I am attaching one of the following forms or attachments
  4. Turbotax has checked the last box:  Form 8949, Sales and Other Dispositions of Capital Assets , if you elect not to report your transactions electronically on Form 8949
  5. Turbotax does not prompt me to print and attach any supporting forms

So, my question is, do I need to attach additional forms, and which ones?

 

If not, do I still need to mail in this form?

 

And lastly, is this a Turbotax bug?  I have reported all of my transactions electronically in this and previous years'returns and never seen this.

 

Thanks!