There isn't a solution - this is how it should function.
The negative number is just part of the summary screen, showing you how much of your state and local tax entered isn't deductible. The negative number itself doesn't go on your return, though you are right it essentially "factors" in because that amount of tax that you paid does not benefit you in anyway.
The program is working as designed - you can't deduct that amount over $10,000 at all, that's just the law.
