Unable to assign sn_hr_core.admin role to any group
London Patch 4 Hot Fix 2
In order to add groups to the role record you should have admin,user_admin and sn_hr_core.admin role. Specifically 'sn_hr_core.admin' should be provided by user who already has 'sn_hr_core.admin' role in order to make this work.
Execute normal change on production to remove and re-add 'sn_hr_core.admin' role to your user as Maint.