After trying to figure out this problem, and being told to turn on physics visualization, I noticed the issue with the old problem. When a property is near my object, the sensor gets triggered. If it collides with it, it works as expected. When near (, with physics visualization on), I could see a yellow cylinder shape connecting the two objects and the sensor triggers. I was originally looking to make this work by collision and only collision, but it also triggers when near the property, but it still doesn't touch! How can I keep the sensor triggering only when the property on another object touches the original object, but not when it is near? Thanks!
EDIT: Ah! I went in to the .blend when I've had time, I've figured out that the problem is the collision type! The "sensor" physics type collides with other materials/proprties not when they collide, but when they are near. Here, take a look! I have a .gif here.