Perhaps you've already indicated the amount that you had (or will have) returned to you. If so, TurboTax won't again present the page asking you to enter the amount returned. I suggest checking line 26 of the IRA Contribution Worksheet to see if it already shows the same amount as line 25. (To do so with online TurboTax, you'll need to download the pdf containing all of your worksheets.) Also, if the net contribution is zero, TurboTax won't include an excess contribution penalty on Form 1040 line 59 for this returned contribution.
I was mistaken that TurboTax asks you to enter the explanation statement following the indication that you will remove the excess (entering the line 26 amount above). TurboTax actually asks for this in the follow-up to entering the code JP 2017 Form 1099-R.
