Perhaps TurboTax is responding to missing data in the MS import, particularly the acquisition date or the sale date. If either of these is missing TurboTax might be responding by putting code M in box 18a and $0 in box 18b of the Form 1099-B Worksheet transaction entry. This code allows either of the dates to be missing but moves the transaction to line 1a or 8a of Schedule D.
Examine a MS transaction entry on the Form 1099-B Worksheet and see if you can manipulate it, perhaps by removing box 18a and 18b entries, to cause the transaction to move from Schedule D line 1a to 1b or 8a to 8b.
