Answer
Check the lobby page's configured client type — from the Lobby page itself, click the padlock icon, then the cogwheel icon, to open its settings dialog, where you can change the client type to Aurena. A lobby configured only for the EE/legacy client type simply won't be listed in Aurena's own lobby selection until its client type includes Aurena. If you want the same lobby content available in both clients, duplicate the page first and set the duplicate's client type to Aurena, keeping the original for EE.