Contributing to an IRA between Jan 1 2019 and April 15 2019: Does the contribution count if it's made after Dec 31, 2018? TurboTax seems to indicate "no".

When I entered the amount of the contribution, my Federal Tax Due dropped. When I entered that same amount in the box for the contribution between Jan 1 and April 15, my Federal Tax Due went back up to the earlier amount. Is this a problem with TurboTax?