Range of hours not working

Under the Time settings I've set the range of  hours blocked to be from 10pm to 7am, yet when my child logged on at 5.10pm  I received a message saying he had logged in during curfew hours. A similar message was received yesterday. Is this a known bug in the software? It seems to work OK for another of my children's accounts.

Under the Time settings I've set the range of  hours blocked to be from 10pm to 7am, yet when my child logged on at 5.10pm  I received a message saying he had logged in during curfew hours. A similar message was received yesterday. Is this a known bug in the software? It seems to work OK for another of my children's accounts.

Time settings.jpgI've attached a screenshot of the time settings and the related activity log. The message was received during the first log in of the day, which was well before the curfew time.Time activity.jpg