Another rear door issue.
They seem more common than I thought. I had the same
problem with my car and had to replace the rear door lock module which was approximately £126 if I recall. Did it myself and wasn't too hard.
The door will open from inside since it's mechanically operated with a cable, the issue with my door not opening from outside was that the central locking unit was sending a signal to the door lock module, I could hear it clicking when I pressed the unlock button on the key fob. The
problem with my lock was that there was a lever that was not moving into position when the door lock was opened, probably a faulty actuator.