Missing motion and short recordings S3 Pro

I have just installed an S3 pro but it only seems to be recording motion in one direction. When someone walks towards the camera - the motion is detected. When someone walks away from the camera - there is no recording.

Also, I have set the camera to record for 90 seconds but sometimes the camera ignores this and records for a much shorter period.

Why are both of these things happening and how do I fix it?

Thanks!