Did you enter $6,800 for property taxes? Are you still employed and paying state or local income taxes? If so, when you entered your W-2 the state and local income taxes were automatically added to the amount you entered for property taxes to come up with your total SALT taxes. If you paid more than $3,200 for your state and local taxes, then this would put you over the SALT limit.
If you ONLY entered property taxes and do not pay any state or local taxes, then you would need to enter $3,400 if that is all you paid for your property taxes instead of the $6,800. You would change this by going back to Your Home and selecting Edit next to property taxes, then change the number to the correct number.