1099-B under Sales Section. Dropdown provides 7 options, last is "Unknown term basis not reported to IRS". If you select you get an error once complete - bug?

[wildew3]

and if you select short or long term (as work around) it will not match the 1099-B... or does that not matter since not reported to IRS?

[DavidD66]

I'm not sure why "Unknown term basis not reported to IRS" is an option.  I've never used it nor I have ever seen it used.  You have to tell the IRS whether your holding period for the asset you sold was long-term or short-term.  Your broker may not know, but you should.  I recommend you use either A) Short-term basis not reported to the IRS (uncovered) or B) Long-term basis not reported to the IRS (uncovered).