Many cities utilize what is called second vehicle detection for left turn bays on the main street approaches to an intersection. The principal behind this is that a single vehicle can usually find a gap in traffic and make a turn during the through movement phase of the signal, thus eliminating the wasted time allotted for a left turn phase for a single vehicle. In the absence of a gap in traffic the vehicle can turn at the end of the green phase for that approach. It appears Mentor is using this technology and therefore nothing is required to be changed at the location. If you want a green arrow for your single vehicle consider stopping back about 20 feet from the stop line.