Ford Fusion: "Blind Spot Detection" Problem

Both my father and my grandparents own Ford Fusions. They both love their cars. But near the entrance to my neighborhood, the "Blind Spot Detection System" goes off on one side. At first, my dad saw the problem, and thought it was just his car. We were still clueless as to why we could drive the entire city of Austin, but only in this spot, the blind spot system didn't work. My grandparents came down to Texas to spend time with us during Christmas, and they had the same problem. Oddly enough, this system still worked on the right side of the vehicle, but not the left. The problem could be a magnetic field, jamming the radar of the system, or it could be the model of car, but we still aren't sure. So, have you heard of this problem? Does this happen to you somewhere in your city? Tell us in the comments down below.