Can't complete IL non-resident return.

I'm trying to finish Illinois non-resident tax return, but TurboTax keeps complaining "Complete your nonresident return(s) first". I repeated several times and answered the questions and even I could see the message like "Nice! Your Illinois return is in great shape". But Illinois return status is still "Started" unlike other states that I'm filing.

How can I check what the problem is?

Thanks in advance,