After you delete your imported 1099 transactions, there is an easier work around. When you manually enter your brokerage statement, you have a choice to "Enter Sales Section Totals" versus entering each transaction.
Then it will ask you to download the PDF of your 1099-B form from your brokerage statement to get filed with your return. Saved all the work of entering many transactions. This worked for me and I was able to bypass the error message.
