Hi Jonas,
Here are my comments and suggestions:
1. Can you try the following script where "DS" is your data source?:
DS.setVariableValueExt("FORMULA_004_MI_IV_OP", min);
DS.setVariableValueExt("FORMULA_001_MI_IV_OP", max);
And just for testing completeness (even though for Formula Variables the external variable format as above is the documented approach), as an alternative:
DS.setVariableValue("FORMULA_004_MI_IV_OP", min);
DS.setVariableValue("FORMULA_001_MI_IV_OP", max);
2. The getVariableValueExt() method is only available at the data source level, as shown below:
DS.getVariableValueExt("FORMULA_004_MI_IV_OP";
DS.getVariableValueExt("FORMULA_001_MI_IV_OP");
Regards,
Mustafa.