I got it started. I use a CH Throttle Quadrant with the axes set for L/R Throttle, L/R Prop and L/R Mixture in that order. My Prop levers actuate what your POH calls Condition levers so I didn't move my Mixture levers off minimum. Since the left engine started, I didn't see this as a problem. I decided to try starting with my Mixture levers full forward and it worked. I looked at datarefs and found that sim/flightmodel2/engines/has_fuel_flow_after_mixture has values of 1,1 when my mixture levers are slightly forward and both fuel valves are open. When I move one full back or close the same engine fuel valve the appropriate value goes to zero. I don't know if that means anything or not.