Just for clarification - when you say the door won't lock, you mean that it will 'latch' and stay closed, but you cannot lock it? That's with both the interior switch, and the remote on the key? How many doors affected?
The problem is that, under the described conditions (parking brake 4 clicks), the remote control will lock all three passenger doors but will NOT lock the driver's door. Additionally the interior light will remain illuminated. You can use the remote to try locking/unlocking all you want, the passenger doors will all work properly but the driver's door will not.
This is 100% repeatable. Depress the parking brake one more click and the problem goes away, all doors lock (with the remote) and the interior light goes off properly.
The central locking system has no connection with either:
1. vehicle movement in gear, fore & aft (post #1)
2. parking brake operation (post # 5)
So their involvement with your fault can only be 'co-incidental'...
1. vehicle movement required me to release the parking brake. When I re-applied the brake I obviously depressed it either 3 clicks or >4 clicks. The movement was a red-herring.
2. Again, this symptom is 100% repeatable and depends solely on the position of the parking brake. Depress the brake 4 clicks...driver's door won't lock. Carefully depress it one more click...driver door locks.
I can understand that you believe that they cause the problem to disappear, but there has to be a more logical reason for this fault. Possibly an intermittent connection on one of the several modules involved in the CL system.
Obviously there's some sort of connection between the parking brake and the central locking system. My guess
is that there is some sort of sensor (perhaps as simple as a switch) that is not fully engaging or disengaging. Clearly something
is sensing the parking brake position and that something is tied into the central locking system. I'll bet that armed with this info the dealer will find the problem immediately.