AngularJs native slide toggle for nested submenues doesn't update height correctly

I'm implementing the a slide toggle for a nested menu in AngularJS. I've been using the code from the following page: https://blog.assaf.co/native-slide-toggle-for-angularjs-1-4-x/

I'm having only one problem with it though. I'm trying to implement this on a sidenav menu with nested submenues, built with <ul> and <li> elements. After having toggled a menu item that has submenu, and I later toggle the submenu of that same menu button, the <ul> element of that menu button doesn't slide in. The height remains the same.

Also, if I keep the submenu closed, and open only the top menu item, the height of the <ul> element remains the same when I toggle the submenu, meaning that the submenu doesn't show until I toggle it open (though remaining invisible), then close the top menu button, then open it again.

Please see it in action here: https://codepen.io/marcus-edensky/pen/MBoWZJ

Here's my JavaScript code:

app.controller('myCtrl', function($scope, $mdSidenav) {
});

app.animation('.slide-toggle', ['$animateCss', function($animateCss) {
    var lastId = 0;
    var _cache = {};

    function getId(el) {
        var id = el[0].getAttribute("data-slide-toggle");
        if (!id) {
            id = ++lastId;
            el[0].setAttribute("data-slide-toggle", id);
        }
        return id;
    }
    function getState(id) {
        var state = _cache[id];
        if (!state) {
            state = {};
            _cache[id] = state;
        }
        return state;
    }

    function generateRunner(closing, state, animator, element, doneFn) {
        return function() {
            state.animating = true;
            state.animator = animator;
            state.doneFn = doneFn;
            animator.start().finally(function() {
                if (closing && state.doneFn === doneFn) {
                    element[0].style.height = '';
                }
                state.animating = false;
                state.animator = undefined;
                state.doneFn();
            });
        }
    }

    return {
        addClass: function(element, className, doneFn) {
            if (className == 'ng-hide') {
                var state = getState(getId(element));
                var height = (state.animating && state.height) ? 
                    state.height : element[0].offsetHeight;

                var animator = $animateCss(element, {
                    from: {height: height + 'px'},
                    to: {height: '0px'}
                });
                if (animator) {
                    if (state.animating) {
                        state.doneFn = 
                          generateRunner(true, 
                                         state, 
                                         animator, 
                                         element, 
                                         doneFn);
                        return state.animator.end();
                    }
                    else {
                        state.height = height;
                        return generateRunner(true, 
                                              state, 
                                              animator, 
                                              element, 
                                              doneFn)();
                    }
                }
            }
            doneFn();
        },
        removeClass: function(element, className, doneFn) {
            if (className == 'ng-hide') {
                var state = getState(getId(element));
                var height = (state.animating && state.height) ?  
                    state.height : element[0].offsetHeight;

                var animator = $animateCss(element, {
                    from: {height: '0px'},
                    to: {height: height + 'px'}
                });

                if (animator) {
                    if (state.animating) {
                        state.doneFn = generateRunner(false, 
                                                      state, 
                                                      animator, 
                                                      element, 
                                                      doneFn);
                        return state.animator.end();
                    }
                    else {
                        state.height = height;
                        return generateRunner(false, 
                                              state, 
                                              animator, 
                                              element, 
                                              doneFn)();
                    }
                }
            }
            doneFn();
        }
    };
}]);



(function() {
    var app = angular.module('app', ['ngAnimate']);

    app.animation('.slide-toggle', ['$animateCss', function($animateCss) {
        return {
            addClass: function(element, className, doneFn) {
                if (className == 'ng-hide') {
                    var animator = $animateCss(element, {                    
                        to: {height: '0px'}
                    });
                    if (animator) {
                        return animator.start().finally(function() {
                            element[0].style.height = '';
                            doneFn();
                        });
                    }
                }
                doneFn();
            },
            removeClass: function(element, className, doneFn) {
                if (className == 'ng-hide') {
                    var height = element[0].offsetHeight;
                    var animator = $animateCss(element, {
                        from: {height: '0px'},
                        to: {height: height + 'px'}
                    });
                    if (animator) {
                     return animator.start().finally(doneFn);
                    }
                }
                doneFn();
            }
        };
    }]);
})();

Here's the HTML - a simple :

<ul class="menu-toggle-list">
    <li><a md-ink-ripple ng-init="showMenu2 = true" ng-click="showMenu2 = !showMenu2" class="md-button menuSub">Tours</a>
        <ul ng-show="showMenu2" class="slide-toggle">
            <li><a md-ink-ripple ng-init="showMenu3 = true" ng-click="showMenu3 = !showMenu3" class="md-button menuSub">Group tours</a>
            <ul ng-show="showMenu3" class="slide-toggle">
                <li><a md-ink-ripple href="URL/TOURS/GROUP-TOURS/PLANNING/" class="md-button">Planning</a></li>
                <li><a md-ink-ripple href="URL/TOURS/GROUP-TOURS/TYPES/" class="md-button">Types</a></li>
            </ul>
            </li>
        </ul>
    </li>
    <li><a md-ink-ripple ng-init="showMenu6 = true" ng-click="showMenu6 = !showMenu6" class="md-button menuSub">Users</a>
        <ul ng-show="showMenu6" class="slide-toggle">
            <li><a md-ink-ripple href="URL/TOURS/GROUP-TOURS/" class="md-button">Staff</a></li>
            <li><a md-ink-ripple href="URL/TOURS/GROUP-TOURS/" class="md-button">Clients</a></li>
        </ul>
    </li>
</ul>

Here's the CSS:

.slide-toggle {
  overflow: hidden;
  transition: all 0.25s; 
}

The parent still holds the height after the animation. You have to remove it.

Add element[0].style.height = 'auto' after animation is done.In the generateRunner function at line 36 after the if

function generateRunner(closing, state, animator, element, doneFn) {
  return function () {
    state.animating = true;
    state.animator = animator;
    state.doneFn = doneFn;
    animator.start().finally(function () {
      if (closing && state.doneFn === doneFn) {
        element[0].style.height = '';
      }
      element[0].style.height = 'auto'; // <----- HERE
      state.animating = false;
      state.animator = undefined;
      state.doneFn();
    });
  }
}

Hope this helps. Good luck!