Mg zs saloon drivers door not locking

As the title says the drivers door of my zs doesn't lock when using the remote. I tried used the key but that set the alarm off. When I unlocked the car I didn't hear the noise of the doors unlocking and had to unlock the passenger door manually. I drove and the car didn't lock but when I stopped and turned off the engine and turned it back on later the doors locked. Although when I stopped and locked the car again the drivers door is unlocked