If you install the Load Balancing plugin against an installation of the Application Server that already has a Load Balancer plugin installed (for example, from 7.1EE), then the 8.2EE plugin will silently replace any existing Load Balancer, even if you have created a new server instance in which to run the plugin.
The plugin files are installed by default under the install_dir/plugins/lbplugin directory, which means that only one version of a plugin can be used with any one Application Server installation. Note that the console installer does display a message indicating that an uninstall is being performed, but this message can sometimes be easy to miss.
Not everyone will encounter this problem. If you do encounter the problem, remove the old Application Server installation and do a fresh install rather than doing an upgrade installation.