I can't see my map services in the REST services directory (e.g. https://gisServer/arcgis/rest/services), although they appeared to successfully publish from Desktop and I can view them from their service end point.
And to ad to Tobias' comment, even if the service isn't secure, if the folder (or root directory) it is in within ArcGIS is secure, you would have to log in to see the folder too.
and just in case.....the service of course needs to be running. REST directory sill not show stopped services, but AGS Manager and viewing thru Catalog will, since you can start/stop/etc in either of those.
The services are in a public directory. Here's an example https://terra.library.brocku.ca/arcgis/rest/services/EarlyNiagara/NiagaraRiver1897NMC113392/ImageSer...
When I connect to terra in Catalog as a public user I can see all of the services and open them in ArcMap but when I login as publisher OR adminstrator I cannot see the services.
My IT guy worked the solution. This was his summary "I ran the configure ArcGIS server account as an admin and reconfigured it again with the default options.". Somehow I think there might be more to it but for now it is working and I can see my services.