There are two possibilities here.
The Maybe Occupied Timeout takes too long or
The room was in the Occupied State after everyone left the room.
In the first case the Entry/Exit Sensor detected the last person out of the room, but the Maybe Occupied Timeout takes too long. If this is true, go to the Room Timeouts Menu and reduce the time of the Maybe Occupied Timeout for the appropriate Room Scene. You will know that you have reduced it too much if "The lights turn off when someone is still in the room" - just after someone left the room.
In the second case, either the Entry/Exit Sensor did not detect the last person out of the room OR the Area Sensor activated after the Entry/Exit Sensor. In either case, the room went into its Occupied State after everyone left the room. The best solution is to make sure that the Entry/Exit Sensor is the last sensor to activate. Recall that the Home Positioning™ System automatically inserts a 5 second delay after the HPS activation of an Entry/Exit Sensor before enabling an Area Sensor to activate. If, for some reason, the Entry/Exit Sensor cannot be the last sensor to activate, then reduce the Occupied Timeout time in the Room Timeouts Menu. You will know you have reduced the time by too much when The lights turn off when someone is still in the room - when someone is sitting quietly in the room.