Thanks for the heads up. I'm having the same issue.
I'm starting to wonder if the current version of Moodle Hub requires subscription to Sendy (a paid private service). It's not mentioned in the documentation so I'm hoping I'm wrong. Can someone correct me?
I successfully adjusted the code for the sake of trying out the plugin. If you want to do the same, comment out the line 204 of "/lib.php" like so:
//update_sendy_list($site);
This will skip updating the remote Sendy list when adding a site to the hub. I'm in no way familiar with this plugin, so obviously I don't recommend doing this hack in a production environment. It's not a solution.
