I tested again. The Problem only occurs und low light conditions. The Logitech kann lower the framerate incrasing the shuttertime. It simply seems not to be limited, how low the framerate can go. Under light conditions I can darken the lens with my hand and after a few moments the framerate will lock to zero. If you pulled the hand away early enough the camera slowly increases framerate again.
I tested again. The Problem only occurs und low light conditions. The Logitech kann lower the framerate incrasing the shuttertime. It simply seems not to be limited, how low the framerate can go. Under light conditions I can darken the lens with my hand and after a few moments the framerate will lock to zero. If you pulled the hand away early enough the camera slowly increases framerate again.