Clicking on the column headers does not sort the column. I've not been able to find it as a topic in this forum, but in digging around in another forum I found discussion that tied the symptom to a template. So, I'm checking to see if that is a possibility. And/or to see if there is a suggested solution.
Are you sure your are posting in product assigned forum?
What is your CMS version?
: Joomla 3.x
Link to installation
Have you edited any files? If yes tell us which ones.
Is this personal or client website?