EuroScope scenario file problem - a/c don't automatically select best exit

Does anyone know the factors that affect the aircraft decision of which exit to take when the route is predefined with ILS27#VR for example? I cannot find a workaround for one particular scenario file at Liverpool (EGGP) runway 27. There is a Rapid Exit Turn off E and a normal turn off D before the final exit at the end C. No matter what the aircraft type, when left to select their own exit, they all go to the end and turn off on C.
If the exits D or E are selected specifically by the pseudopilot, all a/c vacate as directed.
The runway is more or less symmetrical and there are exits F and G on runway 09 and the baffling thing is that the same aircraft in the same scenario but with the predefined routes ending with ILS09#VL all vacate correctly!
Can anyone suggest where I should look for the difference between runway 27 and 09?
Thanks for your help.