Rear Door wont lock/unlock

[a3113]

Hi
One of my rear doors won't lock. I have tried to attach a video to show the issue but it won't let me. The locking mechanism does move a few mm when I press my key fob however not all the way. I can force it with my key so the door stays locked but it won't unlock with the key fob and only unlocks by pulling the handle from inside the car.
The car is a Corsa Ecoflex SE 1.4 2016.
I have sprayed WD40 in there should I keep doing that or try something else? As it moves slightly I suspect it isn't the wiring but could be wrong.
Cheers