Privileged API user cannot view per Unix Cluster the UnixClusterGroup objects

A privileged CO API user cannot view the list of UnixClusterGroup objects per UnixCluster. This call

curl \
-k \
--verbose \
-u 'co_2.rest_user_01:XXXXXXXX' \
-X GET \
'https://registry-dev.skoranda.scgvm.net/registry/unix_cluster/unix_cluster_groups.json?unix_cluster=60' | jq

returns a 401