When using the manual enrollment you have the option of adding cohorts of users. Sometimes these cohorts can have very large numbers of users and take hours to process.

There is a few overlapping issues:

1. When adding a cohort, this is a blocking ajax call which can take hours and block the users session. This should be moved to a progress bar / async
2. When adding a large cohort you are not prompted with anything confirming what you are doing and it is not that hard to accidentally add the wrong cohort, or even add a single cohort when you meant to add a single user. If the number of users about to be added is over a certain threshold is should prompt you with the number of users and confirm
3. The list of cohorts should contain the user counts in the dropdown
4. Many clients use either auth_manual and or auth_cohort and do not require or desire to have manual enrollment of a cohort. If would be good if this could be disabled either as a setting or new capability so that you never get shown the cohorts.