Roles and permissions

Sorry, I thought I had responded on this already. The moodle/course:viewparticipants permission is the one we modified for students within the course in question. It worked in our testing back in February when it was setup, and continues to appear to work in most contexts, but somehow at the random periods of times above, the users indicated were able to view the page without an error message. We initially had just removed the permission (making it "Not Set"), but we have since set it to "Prohibit". In our testing, both methods prevented access to the page and produced an error message.