While it may be inconvenient to not be able to import the transactions, there is a workaround that should assist you in getting the transactions entered in to your return.
The 1099-B you received should have reported to you all transactions and what grouping they are in, such as short-term, covered and not covered, long-term, covered and not covered, and any others that are on the reporting form. The following should help:
AS long as you have a paper copy of the 1099-B, you can enter the data manually by group rather than on a transaction-by-transaction basis. This may not be the ideal solution for you as most would prefer a direct import but this does work. The following screen shows the grouping and your 1099-B will show the transactions per group:
Enter the totals for each group, such as short-term covered, short-term non-covered, etc., and that will enter the data on to Schedule D and/or Form 8949.
The IRS is more concerned with the totals than the individual transactions.
The following link may also help: