You might have to disable audio enhancements on the Vu+ before you open Kodi as these kill the sound.
I had enabled 3D in the audio settings and had them all (bottom 3) set to HDMI. Turning these 3 to
off again as shown below made the sound return to Kodi.
So perhaps all you need to do to fix yours is go to
Menu-Setup-System-Audio Settings and set as shown above.