Binding a given role to a user in OpenShift does not appear to work

Issue

Binding a role to a user does not fail or indicate any error, yet the user is still not able to perform actions permitted within the bound role:

# oc adm policy add-cluster-role-to-user cluster-readers user1

[user1@openshiftmaster01:~]$ oc get images
Error from server (Forbidden): images.image.openshift.io
is forbidden: User "user1" cannot list images.image.openshift.io
at the cluster scope: User "user1" cannot list all images.image.openshift.io in the cluster