Code AG for box 20 does not relate to the 199A deduction, so that is why you are not receiving one on your return. The box 20 codes must be Z, AA, AB, AC or AD. See the screenshot of the K-1 codes I put will put in the answer above. You will need to go back to the preparer of your K-1 to see why the 199A codes were not put on it.
