I have had several individuals ride in my back seat and had never had this problem. So hopefully you just have a setting you need to change and not the dealer for a warranty check.
1.In the center screen panel click on the little house in the upper left.
From there you should see a setting tab to click on.
Next you should see a vehicle setting I think it is. (Sorry going from memory if this is wrong)
Finally I think you will see something about a rear seat occupancy where you can toggle it on or off.
If this don't work try this below
2.Do your rear doors have the child safety locks turned on or off? You will know if you can't open the door from the inside. Maybe affecting your alarm if they are on? Mine are turned off and very simple to do.
So hopefully this helps, good luck.