How to select the regular attributes?

I'm using 'Process Documents from Files'. So I use the operators Tokenize, Transform Cases, Generate n-Grams, Filter Token and Filter Stop words inside 'Process Documents From Files'. On the process I use 'Select Attributes'. But when I choose the attribute filter type 'a subset' and click on the button for selecting attributes, the only atributes I can choose are the special attributes. There was suposed to be 42K columns according to the results... I can choose only like 'label', 'text' 'metadata' but any other columns that appears on the results when I select 'all attributes'.