I have trucks delivering coal, and only coal, to my truck stations, which then feed into Coal Factories. Every so often, Fuel and/or Rotors will suddenly appear at my truck station and then begin feeding into my Coal Factories. Needless to say, my coal factories shutdown and then my whole power networks shutdown. I am sure my trucks are not carrying anything but coal, but yet somehow, other stuff shows up in my truck stations. This is a bug!