1.- Create a new question type EMI whith format "Rich text / Attachments " in a Question Pool.
2.- In this question Enter a option text and Add a Attachment below.
3.- Set the number of options in this question.
4.- Set Item Stems and add a attachment in each either and save.
5.- Import to a assessment the question type EMI from the Questin Pool.
6.- When the question has been copied in the assessment, edit it and you'll see that the format of EMI is "Simple text - for a list of items with no formatting" not "Rich text / Attachments...". If you choose that format "Rich text / Attachments..." the original configuration of the question appears, but without attachments of the Item Stems.