"List of IP addresses and networks that are allowed without auth" not working

I usually use my Plex server unauthenticated. While playing with the parameter, I noticed this one doesn't work: if there is anything valid in this list, clients MUST authenticate, even if their IP address are in the list - and anyway if the server is unauthenticated, the client can't find it after authentication...
(Server version 1.2.7.2987 / embedded web client 2.10.10)