Minimum available date doesn’t work

Hello!

I’m trying to set up Minimum available date.

It works with days correctly. But when I try to edit hours it seems to have no effect whatsoever.

For example, now is 10 am and I have time slots from 10 am to 6 pm.
And I need at least 3-hour notice to prepare for an appointment.

I tried:
now+1 hour
now + 2 hours
now + 4 hours

Whatever I put there the calendar shows the whole range of time slots from 10 am to 6 pm for today.

What am I doing wrong?

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