A correction to my previous post. It only happens when both throttle 1 and throttle 2 joystick levers are moved together. But it results in only simulator lever 2 moving. When only moving joystick lever 1 the sim ignores it, same for lever 2 (when auto throttle on). When moving both joystick levers at the same time the issue occurs.
The implementation of the auto throttle should either ignore any movement of joystick levers or react to any of them individually. At the moment it is impossible the first set the joystick levers in a roughly correct position before disconnecting the auto throttle.
Thanks.