I have set the client settings to highlight contacts in the server tree.
Recently my contacts are only highlighted on TS5 servers.
e. g. Official TeamSpeak Beta Server
On all other servers no one is highlighted.
e. g. Official TeamSpeak Public Community Server
That is due to the fact, that the user tag has changed in the last beta update (beta69) and the ts3 server does not know how to handle the new tag so it does not highlight contacts.
For the old server the old user tag should have been brought back as we noticed that during the testing phase, but it seems like it did not made it into the final beta version (either by design or by priority of other stuff).