I'v had this problem recently. However I found that the problem only occured when I set the start time between midnight 00:00 and 12:59. If I set a start time of 01:00 or later the charge scheduler stopped at the chosen time. To start using the cheap electricity, I would ideally set the start time at 12:30 and finish at 04:30, but i now start at 01:00 and finish at 04:30.
In addition I have often found the car starts to charge immediately I plug in, even though the charge scheduler had been chosen. I now always select continuous charge and then the scheduled charge before I get out of the car and plug in.