I have two furnaces with two similar humidifiers and two similar humidistats. With the furnace off, slowly move the dial on the humidifier from off towards 45 and listen for a "click". That will give you a rough idea of what the humidity is in the house.
To see if the humidifier is working, turn the thermostat to a higher setting than the room temperature so that the furnace goes on. Turn the humidistat to the maximum. Stand near the humidifier. When the furnace blower kicks on to circulation heated air to the living space, you should hear the water going into the humidifier, and, since the humidifier works by pouring water over an evaporator pad, you should see water coming out of the bottom of the humidifier going to a drain, or to a condensate pump. If that is not happening, make sure your water valve is open. You may want to open and close it a few times, especially if it is a saddle valves. As far as the leaking ice concerned, one of mine does that, and, the last I checked, replacing the part (solenoid valve i think) would cost almost as much as a new humidifier. Therefore, I only use one of mine.