Moralis.Cloud.afterLogin() doesn't work!

Moralis General
#1

This cloud function is never triggered:

Moralis.Cloud.afterLogin((request) => {
  // const logger = Moralis.Cloud.getLogger();
  // logger.info(JSON.stringify(request)); 

  const { object: session } = request;
  const user = session.get("user");
  user.set("isOnline", true);
  user.save(null, { useMasterKey: true });
});

Am I missing something?