What do you mean with failing. What is not working for singal02 - is it not detecting parts. As I can see in your picture the signal01 and signal02 is currently forced to a fixed value (the "!" behind the Signal value)?

A sensor (using raycasts) does not need to have colliders because collision is detected by the raycast the sensor is sending out. But the objects which have to be detected need to have a collider.

With a Raycast based Sensor you don't need to use colliders but you need to define the layers where the Raycast is sending to. It is the same Layer as the Sensor is and additional Layers which you can define. 

For a non Raycast (Box Collider) based Sensor - the Sensor should be normally on the layer rvSensor. Please also check the doc information about the collsission matrix for colliders.

Got it - Linux is not supporting Screen.dpi. You should insert this in line 456 in SceneMouseNavigation. It will be part of the next release in 3-4 weeks, for the moment you should change the code manually.

#if (UNITY_EDTOR_LINUX || UNITY_STANDALONE_LINUX)
      DPIScale = 1;
#else
      DPIScale = 144/Screen.dpi;
#endif

You are right - this happens only on Linux - will need to check and get back to you.

You should check our drives and transport surfaces in the demo model. There you could see how it must be setup. Basically each transport surface needs a drive at the same level or at any level above. Please check that the drives have a reference to the transportsurface. Usually this is set automatically: