On Windows, when you open a data frame, the data frame migh have a column whose name is non-ascii character and you may get the erorr something like Evaluation error variable <your_column_name> not found.
This typically happens when your System Encoding does not match with your data.
To workaround this, you can set a System Encoding if you use Exploratory Desktop on Windows.
To set System Encoding, click down arrow icon next to project name and select Configuration from pulldown menu.
Click System Encoding list of value
and select apporpirate Encoding to match your data.
then click OK button to save it.