I had the same issue. You need to also set a time to turn off the charger.
For instance, I wanted to charge between 2:30am and 7am.
When I set it to charge at 2:30am, without a turn off time, I had the same symptoms you are describing.
So try setting a turn-off time of 8am or whatever time you want, then it should be off between 8am and 8pm and on between 8pm and 8am.
Make sense?