Update: I found a solution ... though I can't say if it's the "right" one.
I modified the 1099-B sale information by 1) changing the term to "Short term - basis not reported (noncovered)" ... which matches boxes 5 and 12 on this section of the 1099-B, and 2) in the next screen, checked the "I need to correct the cost basis" checkbox. This fixed the $0 cost basis assumption.
Next, the federal review again stopped and forced me to supply something other than "Blank" for the acquisition date of this security in the 1099-B info ... so I changed it to the only other option: "Various (or more than one date)" ... even though that is not accurate for my 1099-B. This got me passed the federal review without the bad $0 basis.
