When I fly the default Cessna 172 and set the heading bug then turn on the autopilot with the AP button and then press the HDG button, the Cessna flies towards the heading set in the bug as I would expect.
If I then press the HDG button again so that HDG is no longer displayed on the autopilot and change my heading, the autopilot turns me back towards the heading set on the bug.
Is it meant to do this and if so what is the point of being able to turn HDG off?