Since I updated my Galaxy S5 to Marshmallow, it seems that I have to tick the USB debugging box in developer options each time I restart my phone. Otherwise, I can't connect to the MPE software on my PC.
Also is there a way to prevent the connection from always defaulting to USB Charging??
My screen is starting to fail, and I couldn't connect to MPE because I couldn't change the above settings. It is working at this moment, but it will likely fail again before I have the opportunity to either fix it, or purchase a new phone. There must be a work-around, so I can access my phone via USB if the screen fails again.