Firebase on.child_added not firing

As I understand it, querying a ref using child_added does the following:

The child_added event fires once for every existing child and then continues to fire every time a new child is added.

I'm using child_added to query a ref which is populated with items - based on whether a user is signed in or not. For some reason, the function is called - but it doesn't get past ref.child_added - and I can't figure out what is wrong with the query as I've used it successfully before.

<!-- HTML (PLACED AT BOTTOM OF HTML DOC) --> 

<script src="js/firebase.js"></script>     
</body>

// firebase.js

var data = firebase.database().ref('item/');

function getItems(ref){
        console.log("getItem FUNC HAS BEEN CALLED");    // LOGS TO CONSOLE
        console.log("THE REF IS:" + ref);               // LOGS TO CONSOLE
      ref.on("child_added", function(snapshot) {
        console.log("child_added was called");          // DOESN'T LOG
        var artistItem = snapshot.val();

// REST OF FUNCTION
});

    firebase.auth().onAuthStateChanged(firebaseUser => {
            if(firebaseUser) {

                getItems(data);
                console.log('getItems WAS RUN');             // LOGS TO CONSOLE

            } else {
                console.log("NOT LOGGED IN");  // LOGS TO CONSOLE
            }
        });

What is the problem here? I've tried many ways of implementing this function (in terms of placement). What am I missing.