Had the same on mine, cable didn't break it was old and would not always allow the mechanism to reset properly, when opened from inside, worked out if you put the window fully down and with a long metal rod, I could reach down and send home the sticking arm on the actuator, new cable sorted the problem. Though I also replaced the actuator at some point, as the central locking would just engage at random times, it was the drives side causing the issue, the tailgate takes an ground from this actuator, so if it plays up you're locked out of the boot.
Had the same on mine, cable didn't break it was old and would not always allow the mechanism to reset properly, when opened from inside, worked out if you put the window fully down and with a long metal rod, I could reach down and send home the sticking arm on the actuator, new cable sorted the problem.
Though I also replaced the actuator at some point, as the central locking would just engage at random times, it was the drives side causing the issue, the tailgate takes an ground from this actuator, so if it plays up you're locked out of the boot.