trueChart allows BI variables to be used within specific parts of the extension. These variables are evaluated by trueChart.
trueChart only evaluates the required variables used within the extension currently visible on the sheet. These variables are marked with a tick in the first column of the variables list. The list also shows all available variables that could be used in the extension.
You can reevaluate the used variable by clicking the clear icon in the top right corner of the variable list. This will show you only the currently used variable in the cell you see in the preview.