I own a 2011 Porsche Panamera and I have this issue that when I press lock on the car-key, the car isn’t beeping but it is locking. Although it’s not completely locking because I can still open the car door, although the alarm sounds.
try using your other key fob and key to see if you still have the same problem.
The door lock actuator is too weak to lock the door, that is why you don’t hear the lock confirmation beep. Replace the door latch.