Custom alerts from Loki alertingrule shows blank o/p in the Developer window AlertsRules

Steps to reproduce 

1> Create a user tom (example user), give him cluster-admin role.

 
oc get clusterrolebinding -o json | jq '.items[] | select(.subjects[]?.name == "tom") | {name: .metadata.name, role: .roleRef.name}'

2> Create Lokistack and alerting rule  as mentioned in https://access.redhat.com/articles/7096880

3> Now login to the console as Tom >  go to the developer console > Go to Observe > Go to Alerts  > click on loki alert created in previous step > Click on AlertingRule at the bottom of the page Blank page is Seen

(see picture 1,2,3)

Additional pointer

If User is added to cluster-admin group as mentioned in https://docs.openshift.com/container-platform/4.14/observability/logging/log_storage/cluster-logging-loki.html#logging-creating-new-group-cluster-admin-user-role_cluster-logging-loki

 
# oc adm groups new cluster-admin
group.user.openshift.io/cluster-admin created
# oc adm groups add-users cluster-admin jim   
group.user.openshift.io/cluster-admin added: "jim"
# oc adm policy add-cluster-role-to-group cluster-admin cluster-admin
clusterrole.rbac.authorization.k8s.io/cluster-admin added: "cluster-admin"
# oc get groups
NAME            USERS
cluster-admin   jim  

Still when this user go to the developer console > Go to Observe > Go to Alerts  > click on loki alert created in previous step > Click on AlertingRule at the bottom of the page Blank page is Seen 

see picture 4 for this