The issue is that the market filter setting is not being saved. I have narrowed the problem down to the javascript for the individual marking page overriding the markerfilter preference to an empty value. I believe that the bug has been introduced at some point between their old Moodle version (3.4.8?) and the current version 3.8.3. 

 The function that is getting overridden by the JS is in externallib.php. The JS file which is overriding it is in grading_navigation.js

Any other questions let me know. I hope this helps, Thanks.