I’m having the same issue. Contacted TurboTax and they told me to file federal seperate because some forms aren’t available to efile for the state return. Now I’m going back in to try and file my state and it doesn’t let me file it on its own.
This likely means there is a form or multiple forms that aren't ready to be filed just yet. Here is an IRS forms availability table for TurboTax individual (personal) tax products. Also see our FAQ to guide you to the dates tax forms will be available state by state.