The $10,000 limitation on the deductibility of state and local taxes applies to income taxes and property taxes, and alternatively, to sales taxes.
Based on what I have been able to learn about you from your question, I suspect that when you entered the information from your Form(s) W-2, you may have had more than $10,000 in state income tax withholding. If that was the case, when you entered your real estate taxes, the cap had already been exceeded, so the real estate taxes resulted in no change to your itemized deductions or the amount of federal income tax.
Your home mortgage interest caused a change in your federal taxes, because interest is not capped by the amount of interest, but by the principal amount of the mortgage.
"For qualifying debt taken out on or before December 15, 2017, you can only deduct home mortgage interest on up to $1,000,000 ($500,000 if you are married filing separately) of that debt. The only exception is for loans taken out on or before October 13, 1987; see Pub. 936 for more information about loans taken out on or before October 13, 1987."
"For qualifying debt taken out after December 15, 2017, you can only deduct home mortgage interest on up to $750,000 ($375,000 if you are married filing separately) of that debt."
Source: IRS Pub. 530 Tax Information
for Homeowners
