UPDATE: Seems the issue's been solved. Servers should now appear in the Server Browser.

It looks like there's a widespread issue affecting the Server Browser of some commercial games as well as many Source-based mods.

Rather than retrieving a list of online servers, a "There are no internet games listed..." message is displayed instead. The issue might be related to the new SteamCMD utility that's used to patch servers.

Until the problem is fixed, connect to one of our official servers directly ( http://goo.gl/XTTqk ). You can do so by adding them to your Favorites or typing "connect <IP>" in the console.