Apparently there are current issues with the amend function in TurboTax. That may be what's affecting your attempt to amend your state return. See the info below.
https://ttlc.intuit.com/replies/5567856
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***