Buggbairn

Hi all :-) I don't know if I've been overly forceful during our recent cold spell but the passenger door on my 16 plate Octavia is giving me grief. When I unlock the car I cannot gain access through the passenger door. I can however open it from inside and once I've opened it from the inside I can now open and close it no problem from the outside until, that is I've locked it again. At that point I have to go through the whole process of opening it from the inside. The door appears to be securely locking with the rest of the car when I park the vehicle up. Does anyone have any ideas what's going on? Note:- both rear doors are unlocking and opening as they should without any issues.