You must have Authentication turned on for changes on the Client to be synced back to the Server.
Also, some changes can not be done on the Client and synced to the Server, such as many file functions (RM&CF, Covert Art, etc., although file deletions work), changes to Views, and a few other things.
Changes that work from the Client include all metadata changes, as long as they don't involve filename or Cover Art, Playlists, Number of Plays, etc.
There are several threads on the topic, and maybe even a Wiki article. This one, though it isn't a complete list.
https://wiki.jriver.com/index.php/Library_Server_SyncIf you need to make changes on the Server that you can't do from the Client, use Remote Desktop or similar (Teamviewer, VNC, LogMeIn, whatever) to connect to the Server and do it through that connection.