Turk123sky

I have my parking brake set to a toggle switch on my Bravo throttle. I was having the same issue as you. The toggle would not set the brake or worse, it would act intermediately. After taking a close look in the cockpit view I noticed if I switched the toggle slowly the pedals woiuld vibrate in either the "parking brake on" position or the parking brake off position. If I clicked the physical switch "quckly" it worked every time. I think this has to do with how Microsoft Flight Simulator 2020 keeps sending multiple inputs over and over again. This will also mess up setting things like the heading bug. It makes it move in incriments of 10 instead of ones when certain switches are turned on. But for now, I can use this "quick flip" of the toggle switch to overcome the problem. Try pushing the button faster and watch how it reacts to the pedals or virtual switch on the cockpit panel.