Hello and welcome to Justanswer. My name is Danny I am a Automotive Mechanic here to help you with your problem.
This is most likely the rar side drivers door lock actuator
It can be just getting stuck on some plastic. You can remove the door panel and check for any obstructions in the door lock rod
If this is clean try it with the door panel off if it works great than It can be a restriction through the door panel hole
If this doesnt make a difference replace the door lock actuator