Unable to Grade Assignments

by Michael Collier.  

Hi All,

I am using Moodle 3.1.2 (Build: 20160912)

I am having difficulty grading students assignments. When I click on the Grade button for a particular student's assignment I get the message "undefined",  but no assignment (see attached screen shot). When I dismiss the message the wheels keep spinning but nothing else happens.

Any help would be greatly appreciated.

Michael