your using ECC report for approval, in report RPTCORAPP there is include program RPTCOR_ADMINREP_DATA. if you read the code there is structure cor_items_strukt, this structure is not having the employee name field in standard.
And that reason it wil display if employee specify the reason during correction other wise it will be empty if you see in your screen shot last column.
If you want to display employee name you need to customize the report to display additional information as per your requirement.