It was already giving you the Standard Deduction until your Itemized Deductions went over. Apparently you don't have enough deductions.
This year the Standard Deduction will be doubling so many people will be switching to the Standard Deduction. And there is a max 10,000 limit (5,000 MFS) of property tax and state taxes "SALT". And you can only deduct Medical that’s over 7.5% of your AGI. Also the deduction for job expenses have been suspended.
FAQ on 2018 changes https://ttlc.intuit.com/questions/4482394-how-will-tax-reform-affect-my-2018-federal-tax-return
For 2018 the standard deduction amounts are:
Single 12,000 + 1,600 for 65 and over or blind
HOH 18,000 + 1,600 for 65 and over or blind
Joint 24,000+ 1,300 for each 65 and over or blind
Married filing Separate 12,000 + 1,300 for 65 and over or blind