I’ve checked the total of slots rendered it’s the max of hours setted between server side and client side.
So that, if all your days are at least of 8h, you must set in server side
sched.Config.first_hour = 10;
sched.Config.last_hour = 18; //or 17, 16, any number greater than first_hour but lower than first hour + total of hours
Otherwise schedule in server sid would be setted from 0 to 24 hours, and even you set first and last hour from server side, blank slots to 24 hours will be rendered