If you want to hide interval using the ignore_timeline, this interval can’t be a part of the scale step http://prntscr.com/nipv9l
In this case you need to set max step == 1 hour. Only the full cell on the Y-axis can be hidden.
I try to set unworked hours to hide them in the lightbox when I create a new task.
There are settings that can be used for first and last hour in the time select:
Unfortunately, you can’t hide the hour in the middle of the range (like hour == 13)
limit_time_select is also required with configurations above.
Also to hide unworked hours in day and week view.
Day view and week view:
Same configurations, that used for the lightbox:
The hour in the middle of the range can’t be hidden, but you can block it
Additional for the week view to hide whole day: