Hi AK Folks!
I have a pair of Sound Objects in Wwise that live underneath an Actor-Mixer. The play events I've created reference those Sound Objects directly. I've set the playback volume for these sounds at the Actor-Mixer level. When I test in Unreal 4 (PIE), the sounds seem to ignore this mix setting and play back at full volume. If I connect Wwise to Unreal, and then click on the Actor-Mixer, the volume setting updates and the sounds play back at the intended volume. If I instead set mix levels on the Sound Objects themselves, rebuild, and test in Editor, they play back at the appropriate volume.