I was using Windows 10 and downloaded the software (not using the online version). Good news - I did find a solution yesterday which allowed me to file. Like you, I was never able to correct the negative number in the form. I tried to delete or make it 0, but the system wouldn't let me. However, after many attempts with this error, I clicked on my mortgage lender which was listed on the form as well. Once I had that field highlighted, it allowed me to delete the name of the mortgage lender and it fixed the problem. It didn't change the amount of my refund, so I don't think it deleted out the expense - just fixed the error. I hope this works for you as well.
