Same issue, Unity 5.6.1. And no matter what work around I use, issue prevails...

I have resolved this issue by removing custom shader which I added into 'always included shaders' in the Graphics setting! now it builds as normal. hope this helps you guys.

Same issue on 5.5 it doesn't build if I have reflection source on the lighting setting.

Same here :-( It worked for several days but now Unity always freezes after baking

Same issue with 5.3.2. A plane and a box in the scene. Android. Didn't add any reflection probes, but freezes after building. Seems fixed in 5.4, ,but can't update project to 5.4 at this time.

I don't have any reflection probes, just a Directional Light and it freezes in "Copying and extracting reflection probes...." It's been 30 minutes and counting....

Just a car, a ground (plane with texture), a direction light with Non-Directional on Lighting Settings, Generate UV Maps checked, static unchecked, i putted all inside a GameObject with 0.1 scale, texels to 1, and.....still stuck....

Oh.....my.....

I encountered this issue with my own project. On Mac, build settings iOS, when the scene is set to auto bake then either opening the scene, or attempting to build and run, then the editor would freeze when it came to the reflection probes.

Using source control I turned off auto bake on the scene and was then able to open the scene, and using the manual bake worked on the Mac, and I was also then able to build and run the project, so it seems that is a specific issue with Auto bake.

iMac 21.5 Late 2013 OS X El Capitan (10.11.3)
Unity 5.3.1f (pro)

I'm having the same issue on 5.3.0f4

I am working on Android Project platform and having same problem. Unity version: 5.2.2

p.s. I'm using unity 5.1.2f1 personal.