I am having the same issue. My company just got this program, we are trying to use it but we are having the same problem. It's been a month since this response...no fixes? or not supporting it on CC2015? Any help on this would be greatly appreciated, thanks!

I've found the solution at least in my case. The reason for json file to be empty is that some of the layers were named not in English (Russian in my case). Once I've renamed, the layers it all worked just fine.

the script crashed on ps cs6 and ps cc

Hi is there a fix to this problem i have ps cc 2015
and the script keeps crashing on me

Yea it "works" fine with CC2015, so it must be a layer naming issue or some sort of language problem. I of course am a very basic, bland English user who names all layers with underscores.. no spaces etc. Try naming all images with camel case or _ like, RightArm, Right_Arm, or right_arm

Doesn´t work on CC2015. Tried renaming layers, my Photoshop is in English, every time I try running the script it just crashes. Is there a fix coming soon?