Built-in Function str() doesn't work in List element

Hello,

If I add str("pdf.text.total") in to the list element. It doesn't work.
But if I add str("pdf.text.total") outside the list element, it works perfectly fine.
Also if you have Table element inside the List element, the str("pdf.text.total") works fine. But somehow I tried to many times in different projects to add any kind of localization with str() it never worked with a List Element.

Does anyone know why this happens ? Should there be any kind of paths set to localization repository ? Or just simple why it works in every element except the List one