VMware NSX 4.1.X
This occurs due to a change in the way security group permissions are checked and validated within this version. Previously existing security groups that are bound to firewall rules may become uneditable with the above symptoms.
This issue is resolved in VMware NSX 4.2.1, available at Broadcom downloads.
If you are having difficulty finding and downloading software, please review the Download Broadcom products and software KB.
Workaround
GET /
infra/domains/<domain-id>/groups/<group-id>
UT /infra/domains/<domain-id>/groups/<group-id>