There are sensors in each seat bottom that are supposed to sense the presence of a human sitting there. I noticed when my wife and son sat in row 2, those two seats grayed-out, but I was still able to adjust the seat they did not occupy.
What is happening is your car seat is heavy enough to trigger the weight sensor so the code thinks there is a human sitting there. I suggest you email this to
[email protected] - perhaps they can fine-tune their code to differentiate between a human and a car seat??