Moodle 2.5 - students cannot see marks criterion in assignments with marking scheme

I've upgraded our site to moodle 2.5.2 and I have run into an issue with assignments which use marking schemes. 

Even when an assignment is set to 'Show marks per criterion to students' the marks do not appear on the student view (they appear for teacher role)

I don't see any issue with system roles etc

Anyone encountered this (or replicate it?)

Thanks

Daniel