Gah forgot your not on 5.5.
Is anyone else on 5.5? Can anyone confirm the normals work as expected for them?
It's possible that for some reason UNITY_REVERSED_Z isn't defined when using vertex lighting in 5.4 on android (thats the platform your running right?). That seems super weird / unlikely but running out of ideas.
If that is the case then that's a bug with Unity and not something I can really fix, I will try and check android on 5.5 at somepoint to make sure it's not a prob with that as well.