Global variables in Study Property JSON input vs. Batch Property JSON input

Hello,

I programmed my experiment using jspsych. Depending on the value of certain variables, a different version of the experiment will be executed (e.g. the response button assignment can be changed). I define these variables using the JSON input in the Jatos GUI. However, the experiment only runs if I define these variables in the Study Property part.

If I define them in the Batch Property part the experiment won't start and I receive a warning:

In the experiment I call these variables within the jatos.onLoad(function()):

global_variables =jatos.studyJsonInput;
button = global_variables.button;

I would prefer to define these variables in a Batch instead of cloning my experiment and thereby defining several versions of the experiment by setting the variables differently in the GUI. Why is this not working?