I use UE4.16.2 & Wwise2017.1.0.6302
After upgrading to Wwise2017, I was in the same state as this question.
I ended up uninstalling integration and reinstalling the integration 2017.1 via the Wwise Launcher.
I could not solve the problem and a different error came up.
'sound with positioning enabled is not attached to any listener, will use virtual voice setting' is displayed in the profiler.
Do you have any clues for me?
Please ask me anything if you need more information.