Hello Kevin,
we use version 1.3.57 on Wordpress Multisite, it's activated only on one of the sites.
In Roles > Options > Advanced > Role Assignment Interface there is no "Users CSV Entry". I had to search the plugin code for scoper_get_option( 'user_role_assignment_csv' ) and replace it with true. To enable this.
And that actually didn't switched the interface to CSV editing - but at least thousands of checkboxes were not appearing. We have around 3,000 users, so at least it's not all appearing when you edit a page.
Could you please double check if this still works in the recent plugin versions?
Thanks,
Martin