I may be a bit late to the party, but I was having the same issue when I started trying to package a previously windows only project for android. It was because I had no platform data for android. I fixed it by:
- Adding android as a platfrom in the wwise project
- generating sound data in unreal editor
That fixed almost all the warnings (and got audio working), the remaining warnings were cleaned up by using the clear wwise sound data thing to "Clear orphaned Unreal wwise media assets".