More info is going to be needed for someone to help you. First, what TurboTax product edition are you using, and is it the desktop or Online TurboTax version?
Where do you see "Not started?" i.e., next to what topic/subtopic does it say "not started?"
Have you answered the preliminary rental property questions at the start of the rental interview, which appear prior to entering rental income and expenses, such as the property location, material participation questions, etc.?
If desktop version, are you trying to use Forms Mode instead of the recommended interview mode?