Welcome and I would check the vehicle settings of the car for Lock operation. To do so: get in the car, turn on the key. There is a config button on the radio/stereo. Press that and you will be given a list of options. One of them is Vehicle settings and once pressed there is an option for Locking. I can only imagine there is a setting for which doors to unlock when using the FOB. I know there are like settings for locking/unlocking once you are in the car and turn off the key etc.