Firebase Web - Updating Multiple Fields?

I have the following code where I want to update some simple values in my Firebase database using the Javascript, Web SDK.

However, it doesn't run/update my database. Whats wrong here? Thanks.

    var dbRef = firebase.database().ref().child('feeds').child(selectedFeed).child('audio');
    var uid = dbRef.push().key;

    var data = {
      "downloadURL": uploadTask.snapshot.downloadURL,
      "fileName": file.name,
      "timeStamp": selectedDateUnix
    };

    var updates = {};
    updates["mostRecentKey"] = uid;
    updates[uid] = data;

    dbRef.update(updates).then(function(){
      //success
      alert("Successfully Uploaded. This is now available to be listened to by your users.");

    }).catch(function(error){
      //failure
      alert(error.message);

    });