The date form element in catalog does not allowing to pick the time and its defaulting it to 00:00 all the time.
Will be fixed in RU2 for 17.1 or in 17.2
Also in T6D8377 which can be provided by support
(Update: T6D8377 is now superceded by T6D8380 which also includes this fix).
People have mentioned that the "today" button works slightly differently than older versions.
This button will navigate to the current date on the calendar but it will not automatically select that date.
You must still click on it.