You
You still use the 8949 to report the transactions, even if the basis has already been reported to IRS.
transactions not reported to IRS - category C or F
transactions with basis not reported to IRS - category B or E
Make sure your transaction entries are put into the correct Box Categories.
this is what happens if you import from a brokerage. TT has had this issue for years. if you imported you need to delete the import then use the 1099-B worksheet to enter the summary for the transactions with basis reported