Is the ban process working correctly?

I recently banned one of our users on a timed ban and was expecting them to be automatically unbanned once the timeframe had elapsed. 

However, this wasn't the case! I had to go in an manually unban their account. 

The banned user sees a message on their screen when attempting to log in to inform them of the ban duration and it also includes a timestamp. Again I was expecting the user to be auto unbanned once that time was reached but it didn't happen.

Is there an issue with it (i.e. a bug) or does it just not work in the way I expected/assumed it does?