Hi, we solved this by disabling the "create the wwiseglobal gameobject on every scene" option in wwise plugin settings, then creating a duplicate of the wwiseglobal object, renamed it to wwiseInitializer (the name change is needed since the wwise plugin will delete every wwiseglobal gameobject it encounters because of the previous changed setting) and putting our new prefab manually on every scene.
The problem is probably because strangely the unique instance and DontDestroyOnLoad logic in the AkInitializer is not working correctly on our Unity 5.4.0. So when we start the game on a scene with the wwiseglobal object and load a new scene, the AkInitializer is probably trying to initialize wwise again and reserve memory and everything again thus triggering the access violation error.
I hope this helps someone with our same problem, we've had it for months now.