This looks like a bug in TT. Go to Forms mode and select the K-1 Partner worksheet for the MLP that has the Ordinary Gain. Scroll down to Section D. The first question says "Does this K-1 include a Section 199A Business?". ''No' is checked by default. Switch it to 'yes' and you'll see the rest of Section D populate. You'll also see the Ordinary Gain is put to use for the QBI calculation.
Note that if you switch back to interview mode, and go edit that K-1 again, you'll see several questions suddenly added to the end of the interview, specifically dealing with using the Ordinary Gain for QBI. That's what suggests to me that its a bug -- it looks like TT hasn't added the prompt yet to ask about this during the interview.
EDITED TO CORRECT:
This solution doesn't always work correctly. As pointed out below by tiger425, Section D is the correct place to handle.
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**Note also, I'm not a Tax Preparer/CPA. Just a volunteer, seasoned, TurboTax user.
Use any advice accordingly!
