I'm using App42-Unity3D-SDK-4.1.2.dll. It seems like there is a significant problem right now with the the SDK and specifically that the SDK relies on an older version of the SimpleJSON class (http://wiki.unity3d.com/index.php/SimpleJSON). The version of this class used in your SDK is outdated such that it creates some problems for us.
Specifically, if you save an array of empty string values like ["", "", ""] and then try to create a JSONClass ((ie JSONClass)JSON.Parse(fileData)), it will not read the "" empty values and result in an empty array . You can try it yourself.
After looking at this link - http://wiki.unity3d.com/index.php/SimpleJSON, I can see that this bug was fixed in * [2017-04-11 Update], as it says:
* - Fixed parsing bug where empty string values have been ignored.
I would appreciate very much if you could update the Unity SDK by implementing the latest SimpleJSON class.