Some additional information:

The red error box gives me this message "Form 8949 check box has an invalid selection for . "C" or "F" are the only valid selections for a worksheet with transactions not reported to the IRS".  Nothing I've selected on Sch D or 1099-B indicate transactions are not reported.  So I have no idea why the program thinks Code A is unacceptable.

I've also had this happen on at least 3 taxes so far.  So this is not related to a bug on a single tax file.