Hi Mike, for effects in an aux bus, the dry signal is always ignored. The wet signal is played at whichever level is determined in the aux send level. Game-defined aux-send just means that you do not decide in Wwise which aux send is being used- the game will route to certain aux buses at run-time, usually based on defined envornments within your game level. If you're still hearing 100% of your dry signal at maximum distance, check to see that you have a proper attenuation curve in the position properties. Futhermore- you can determine in the attenuation editor if the aux send level follows the same attenuation as the dry signal, or have its own attenuation curve (this way you can allow the wet signal to remain louder even if the sound is further away).
I hope this helps, Cheers!