It's most likely a rounding error. Remember, the IRS requires that all numbers be rounded to the nearest dollar. So TurboTax rounds those numbers for you. If the rounded numbers come out a dollar or two different from the total on the 1099-K (which they almost always do) then the program makes the math mistake for itself.
Go through all of your numbers from the 1099-K and round them to the nearest dollar yourself. Then total them up. Then take a dollar away from a couple to make the numbers match.
If you are reporting personal item sales from the receipt of an IRS form 1099-K, the software prompts you to enter one or more lines of data into a 1099-B worksheet and an IRS form 8949 / Capital D Capital Gains and Losses.
Are you able to view the tax return to compare the amounts from column (d) Proceed (sales price) on IRS form 8949 to the income reported on an IRS form 1099-K?
In the online versions, you may view or print at Tax Tools / Print Center / Print, save or preview this year's return / Include government and TurboTax worksheets after you have paid for the software.
In the Desktop versions, one can look at the tax return by clicking FORMS, or by viewing the PDF through the Print Center.
I am getting the same error the amount in my 1099-K matches the amount in form 1099-B (Form 1099-K reconciliation). I am going around in circles trying to address this with no luck.