[IvanK]

On these (IRL) Hurricanes and Spitfires the Mixture controls were 2 Position not fully variable.
So think of them as "Auto Rich" or "Auto Lean" that you find on many aeroplanes. So in Lean for example you are in effect just saying I want to run in Auto Lean then using this as a Datum the mixture is automatically leaned as altitude is increased and enriched as altitude decreases. There is no need to be manually adjusting mixture as you climb. In general Weak (Auto Lean) is only going to be used when you want max range or endurance, in Combat you want RICH. Typically there are boost limitations associated with particular mixture selections

In addition the RICH position is at the REAR and WEAK position FORWARD. Also the quadrant was so designed that if the Throttle is brought back to idle it will also drag the mixture lever BACK to its RICH position. You can see this in operation on the Second selectable Hurricane.

The First selectable Hurricane is bugged as the Throttle slides ghost like through the Mixture lever. in the case of the Spitfires its bugged as the Throttle does not drag the mixture lever back. Devs are aware of these bugs

Some of the "rough" running we see is the engine being way to sensitive to the -ve G cut. At present a controlled slow (like around 0.8G) nose lowering has the engine coughing. This sensitivity needs to be fixed so normal smooth attitude changes can be accomplished without the coughing we now see with the slightest lowering of the nose.