I believe I found a bug with setting the hours for an exception day. Every now and then I would like to schedule availability for a worker on a weekend, say Saturday from 3:00 to 6:00. I set those times for the worker on that day, with the Work? value to no. Then I add the exception day(s) as appropriate.
The problem appears if the latest work time for a normal day is before 6:00 - e.g. say it is 5:00. Now the available times shown for Saturday only go from 3:00 to 5:00 instead of 3:00 to 6:00.
I hope you can put a fix in for this problem soon.