I have a group that I created a few months ago and I'm now trying to modify its privileges. I am the JSS administrator and have verified that I'm am in the administrators group. However, all of the privileges for the group I'm attempting to modify are greyed out when I switch to edit mode. I can adjust the membership of the group though, which is curious. If I change the group's Privilege Set from Administrator to Custom, it appears I can then make changes to the privileges. I'd rather start from Administrators, where it's at now and make it custom by removing privileges, as necessary.
I've not seen this behavior before. Our JSS is self-hosted on-prem on Windows 2012r2 and we're still running JSS 9.99.0-t1494340586.