As noted, the Wisconsin Schedule I (Adjustments to Convert 2018 Federal Adjusted Gross Income and Itemized Deductions to the Amounts Allowable for Wisconsin) is not yet ready in TurboTax. This is because TurboTax has to not only get the forms approved by the state but must also code and test the software that supports that form. As you can see, there must be a time lag between the time the state initially releases the form and when TurboTax can declare it "available" in its software.
You can follow Schedule I's progress by looking at the State Forms Availability page.
I looked on the page for when Schedule 1's will be available and it says WI is available, however, I still can't e-file via TurboTax. Any idea why?
If you are having issues and need assistance, please contact customer support. Please see the Customer Support phone number here. If you would like to reach out through our website, please see the TurboTax FAQ below for contact information: https://support.turbotax.intuit.com/contact/