From another post with the same type of problem:
'There actually may be two places to click "Add a State". Did you use one that is visible on the Tax Home page? If so, try this other method. In the left menu column, click on Previous Taxes, which should take you to a section called "Your Tax Returns & Documents." Expand that section, if necessary. Choose tax year 2018. Is there another "Add a State" link there? If so, try that one.'
I hope that helps.
