I'm having the same issue. For me, I'm using the Logitech/Saitek throttle quadrant. When I first start the plane the throttle is in ground idle, but once I advance the throttle past the flight idle marker it won't go back down to ground idle. This also means I can't use the reversers either. I see there are the latches on the throttle which I assume is supposed to be used to allow the throttle to go back down but I can't figure out how to use them. I can click them so that the latches move up but I don't know how I'm supposed to move the throttle back down at the same time, it's impossible. I looked for Saab commands in the controls menu but I didn't see any for the latches. How do I get the throttle back down?
Also, why won't the yaw dampers engage? When I try to turn it on by moving the sliders up, they just slide back down again in the off position.