I put in the square footage for my home office where it says to. When I try to submit my return it loops back to that section.Can't fix it and file.No state tax return.

I have a home office.  I put in the square footage where it says to.  When I try to submit my return it loops me back to that section.  No matter what I do, I can't fix it and file.  If I go back to that section myself, there is nothing to fix.  Line  C says enter square footage or 300, whichever is less.  It does not matter which number I enter, it loops me back.  That is the only thing  stopping mt from filing.  This is crazy!  I think Turbo Tax has an error.   Please help.

Using Turbo Tax home and Business 2018