We have a Search Head Cluster. The three search head cluster (SHC) members have the Indexers listed in the Search Peer.
Everything looks good configuration wise but none of our existing indexes (we had a standalone search head we are using while we set up the SHC) are available to select when accessing a role or creating a new role.
I thought there was an article about this in Splunk Answers yesterday, but I could not find it again.
This was fixed in 7.0.8 and recent releases of 7.2. To workaround this in earlier versions, either add the indexes to your search head or go grab an authorize_roles.xml from a 6.x version and deploy it to your SHC manually in etc/apps/search/local/data/ui/manager