If you have set the Motion Sensor to turn the frame off after a set amount of time, then it should do exactly that, provided there is no physical movement around the frame within the set time.
On rare occasions, you may find that your frame is not switching off. A known cause of this is close proximity of your frame to an air conditioning or heating unit. The frame’s built-in infrared sensor is looking for changes in infrared energy caused by movement. However, as the sensor is sensitive to changes in temperature, it would include the air conditioner as an object with motion or activity.
For this reason, we recommend that you don’t place your frame near air conditioners or heat emitting devices.