Schedule (Illinois Credits) ICR requiring 4.d. fill-in when there is nothing to fill in

I accidentally typed information in 4.d., deleted it, and now Turbotax is requiring 4.d. to be filled in, and says that the form is not complete. How do I clear this error? I tried rerunning the check function, but the program still says it needs to be filled in. What happens if I submit my taxes (if it lets me) with this field not filled in?  Otherwise, how do I reset and refill ICR?  I've been using this form for years and did not have an issue before.