Ionic Cloud Custom Data ionicUser.set() bad request


I am having trouble writing a service to update $ionicUser custom data. When the user logs in I can use the function to save a ‘favorite’ and then call $ with no problem. When I go to update using $ionicUser.set(‘favorites’, data) and the try $; it throws an error: PATCH 400 (BAD REQUEST) I can use a .get to request the data no problem. But I cannot for the life of me update it.
addFavorite: function(item) {
$ionicUser.load().then(function() {
// success!
for(var i = 0; i < favoritesService.favorites.length; i++) {
if(favoritesService.favorites[i] === item) {
$ionicUser.set(‘favorites’, favoritesService.favorites);