Could not add user to "admins" group

Describe the bug
I want to add new user to admins user group via REST API v2, but PATCH request fails with 400 code FIELD_INVALID_CHOICE

To Reproduce
Steps to reproduce the behavior:

curl -X 'PATCH' \
  'https://10.1.20.200/api/v2/user/group' \
  -H 'accept: application/json' \
  -H 'x-api-key: XXXXXXXXXXXX' \
  -H 'Content-Type: application/json' \
  -d '{
  "id": 1,
  "name": "admins",
  "scope": "system",
  "description": "System Administrators",
  "member": [
    "admin", "baz"
  ],
  "priv": [
    "page-all"
  ]
}'

Expected behavior
User baz should be added to the group admins

Screenshots or Response

{
  "code": 400,
  "status": "bad request",
  "response_id": "FIELD_INVALID_CHOICE",
  "message": "Field `scope` must be one of [local, remote]",
  "data": []
}

pfSense Version & Package Version:

pfSense Version: [e.g. pfSense 2.8.1]
Package Version [e.g. v2.6.2]

Affected Endpoints:

URL: [e.g. /api/v2/user/group]