Why is Qualified Tuition Program(QTP) computation of taxable distribution amount wrong?

In the QTP Contribution of Taxable Distributions section of the 1099-Q, lines 3-7, TurboTax computes the taxable earnings portion of your QTP distribution, but it doesn't match the true taxable earnings.

For example, $23,000 distributed, $20,000 education expenses.  Leaves $3,000 taxable.  I know that the taxable earnings on this $3,000 distribution was $1,111.93 because I have it on the ScholarShare (CA) statement.

However, TT does it's own computation on lines 3-7 which yields a slightly higher $1,128 taxable earnings.

Is there any way to override this computation and tell TT what the taxable amount is?  I know it is pro-rating, but that actually produced an incorrect amount.  Bug or works as intended?  Because there are so many variables?  Could the ask a question?  "You have $3000 of excess distribution.  Do you want to enter the basis or have TT perform the computation?"