Pressure Plate bug

That's not a bug, but an intended feature. Activated logic signals are always above non-activated logic signals. The model hider will keep getting an active logic from the pressure plate, so the Lever won't 'work'. Thanks for reporting though!

If you need that to work for a logic system you always can use an And Cube. Then you have to connect the Pressure Plate and the Lever to the And Cube, and the And Cube to the Model Cube. On that way the Model Cube will only work when both the Lever and the Pressure Plate are giving an active logic signal.