I suspect that isn't a .docx file but rather a file of some other sort renamed with the .docx extension. I agree with Emma. Except, if you can't right click and download, you'll need to delete the attempt and have a real .docx uploaded again.
Assignment
Cannot Download Submmited Assignment Moodle 3.5.2
Αυτή η συζήτηση κλειδώθηκε κι έτσι δεν μπορείτε να απαντήσετε σε αυτή.