Our internal moodle page currently has a cohort of 464 members. When I add the enrolment method "cohort sync" in a course and try to select the mentioned large cohort and try to "add method", it loads for ca. 30 seconds before giving me a 500- internal server error.

Reloading the page only leads to an error: "A required parameter (courseid) was missing".

Then I'am able to klick on the button "Continue". When I go back to the enrolment methods settings again the appropriate cohort is there. But when I select the appropriate course group only one member is there.

If I do all this again, but with a smaller cohort (151 members), everything works as it should. Could it be that moodle does not support cohorts of this size?