This issue is about the new assignment type (using versions 2.3 & 2.4.1).
This is only happening in one course where there are 90+ students enrolled.
When the teacher clicks on the View/grade submissions link it takes quite a long time to load the page (it will not load for her at all). When the page does finally load it is just text and does not have all of the expected functionality.
I am unable to view all of the students on that page, nor can I navigate to other pages. It takes about 4-5 minutes to get even that far.
It was happing in just one assignment previously and now it's come up again and is causing some issues for the teacher/students.
I've tried eliminative items that would appear in that column by shutting off submission comments & files.
It is only accepting online text submissions and allowing teacher comments.
All I get from debugging is this:
Fatal error: Maximum execution time of 600 seconds exceeded in /var/www/moodle/lib/htmlpurifier/HTMLPurifier/Strategy/MakeWellFormed.php on line 493