Unloading Lightmaps correctly when using LoadLevelAdditiveAsync

I’m creating a game where scenes are streamed in seamlessly in the background while the current scene is being played. (LoadLevelAdditiveAsync)

The problem comes when I’m transitioning between scenes. Scene 2 loads fine but the lightmap from scene 1 sticks around. I’ve tried Application.UnloadLevel, Resources.UnloadUnusedAssets and setting LightmapSettings.lightmaps = new LightmapData[0]; but none of them seem to make a difference.

I’m using Unity 5.2 with it’s new multi scene lightmap baking.

Any help would be greatly appreciated!!

I’m interested as I’m currently using the same workflow.
Pardon my ignorance, but how can you tell the lightmap is still loaded ?