This is not a malfunction. Camera recordings for the same camera cannot overlap, therefore if the sensor is triggered multiple times, recordings may be shorter than anticipated.
In the example below, the hub is configured to record 10 minutes of camera video when the motion sensor is triggered. The sensor was triggered at 12:00 and the hub recorded 10 minutes of video. When the sensor was triggered again at 12:05, recording was already underway, so the hub waited until 12:10 (when the first recording stopped) and recorded 5 minutes from the second trigger.
The first recording is 10 minutes long, and the second is 5 minutes long.
Sensor was triggered
Overlap (already recording)