When I click on Bake (On demand), unity send me this message:
Could not create lightmap snapshot asset at ‘Assets/test1/LightmapSnapshot.asset’. Failed to collect hash files!
On iterative mode; I don’t see GI in action when I change something in my scene.
?
edit : ok I found the problem…
Care to share your solution? I ran into the same problem.
Yeah would also be interested in the solution, because I just encountered the same problem 
Found the solution in the new included documentation.
In your Unity5 folder: Editor/Data/Documentation/html/en/Manual/GlobalIllumination.html
Simply put, you need deferred lightning for it to work.
That’s strange… I had deferred lighting enabled and it worked before. The error occurred after I emptied the GI Cache.
The solution for me was just to switch my assets to static 
Thanks for the reply. Seems to have fixed it
If you have a way of reproducing this, please file a bug.
Thanks!