Workshop

We're still on v1.33 here at Earlham and I'm just using the Workshop module at the end of the semester. it's really great. A major hitch was the hiccuping on punctuation in assessments - it's amazing how many apostrophe's creep in
 
A major problem has emerged however - I told the students that if the assessment 'crashed out' - as it was doing when they entered punctuation - they could go back in and edit their assessment. Initially, this proved possible but after a couple of days they cannot now do this and some students are left with assignments that have been incompletely graded. I have tried poking about but I cannot seem to re-enable  'Edit assessment' . Any ideas on how this can be done or a workaround?
Ta
Mark P