"Boot" not shutting properly

I own a Skoda Superb Elegance Diesel 2015 reg.  I've owned the car from new.  This is not the estate version but the one that could loosely be called a hatchback.  The "door" at the back has two opening modes 1) a full hatchback and 2) and as a saloon boot.  These are operated by two different switches at the rear of the car.

Out of the blue the boot now jumps loose when driving over a minor obstacle such as a small pothole.  There appears to be a safety catch that prevents the boot becoming completely loose.

The help I'm seeking is why is this happening and what can I do to stop it happening.

Thanks in anticipation.

Peter