Are you talking about a 2018 tax return that you filed with TurboTax Online last year (in 2019)? As DoninGA pointed out, you cannot be doing a 2018 tax return in TurboTax Online now. Did you get an IRS notice about reporting your 2017 state tax refund on your 2018 tax return?
It's impossible to tell why the state refund was not reported without being able to see your 2017 and 2018 tax returns, and we can't see them here. The fact that you itemized deductions for 2017 does not, by itself, mean that your 2017 state refund is taxable on your 2018 federal tax return. Many other factors come into play. In the PDF of your 2018 tax return with all forms and worksheets, you can look at the State and Local Income Tax Refund Worksheet to see how TurboTax determined that the refund is not taxable. At the top of the worksheet it will show the refund amount that you entered.
