You may like to check your input again.  If these are covered securities and meet the conditions for Exception 1, these will flow directly to Sch D, lines 1a and 8a.  These will not trigger a F.8949 and no attachment will need to be e-filed.

Here's an example of how it works.  As you can see, there's no F.8949 and the summary result of the first three transactions flow directly to Line 1a, Sch D, whereas the last transaction goes to Line 8a.