Cisco AAA/Identity/Nac :: Can't Add AD Groups In ACS 5.2


I've run into an annoying issue with my ACS 5.2 install. I can no longer add directory groups in the AD settings, the ACS comes back with "The item you  are trying to delete is referenced by other items.You must remove all references to this item before it can be deleted." but I am not deleting any group, just adding.
Could probably be cleared with removing the AD setup completely, which for obvious reasons is not something I want to do.