Why has my shared element transition stopped working?

Question

My app used to have a shared element transition from a fragment to an activity. I am not sure exactly when it stopped working. I have made minor code changes, but nothing that affects the code around the transitions. The biggest thing I have done is update my support libraries to v24.2.1 (from v23.3.0). I am wondering if I am just overlooking something silly, or if the support library change did something. Relevant code snippets follow:

The code that starts the shared element transition:

public void PreviewClicked(object sender, EventArgs e)
{
    var intent = new Intent(Activity, typeof(RoutineActivity));
    intent.PutExtra(RoutineBundleKeys.BLOB_ID, _selectedBlobId.ToString());
    intent.PutExtra(RoutineBundleKeys.ROUTINE_TITLE, _selectedTitle);
    intent.PutExtra(RoutineBundleKeys.ROUTINE_HTML, ViewModel.Html);

    if (Build.VERSION.SdkInt >= BuildVersionCodes.Lollipop)
    {
        _selectedPreview.TransitionGroup = true;
        ActivityOptionsCompat options = ActivityOptionsCompat.MakeSceneTransitionAnimation(Activity, 
                                                                                           _selectedPreview, 
                                                                                           "webview_preview_transition");
        StartActivity(intent, options.ToBundle());
    }
    else
    {
        StartActivity(intent);
    }
}

And the XML element that is being shared (_selectedPreview in the snippet above):

<WebView
    android:id="@+id/routine_preview"
    android:layout_width="match_parent"
    android:layout_height="100dp"
    android:gravity="center_vertical"
    android:scrollbars="none"
    android:transitionName="webview_preview_transition" />

The OnCreate method in the finishing Activity:

protected override void OnCreate(Bundle savedInstanceState)
{
    base.OnCreate(savedInstanceState);

    SetContentView(Resource.Layout.routine_activity_layout);

    _routineTitle = Intent.GetStringExtra(RoutineBundleKeys.ROUTINE_TITLE);

    var titleToolbar = FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.doc_title_toolbar);
    SetSupportActionBar(titleToolbar);
    SupportActionBar.Title = _routineTitle;

    _htmlString = Intent.GetStringExtra(RoutineBundleKeys.ROUTINE_HTML);

    if (_htmlString != null)
    {
        _routineView = FindViewById<WebView>(Resource.Id.routine_frame);

        if (Build.VERSION.SdkInt >= BuildVersionCodes.Lollipop)
        {
            _routineView.TransitionGroup = true;
        }

        _routineView.Settings.BuiltInZoomControls = true;
        _routineView.Settings.DisplayZoomControls = false;

        string mimeType = "text/html";
        string encoding = "UTF-8";
        _routineView.LoadDataWithBaseURL("", _htmlString, mimeType, encoding, "");
    }
    else
    {
        var blobIdString = Intent.GetStringExtra(RoutineBundleKeys.BLOB_ID);
        _blobId = new Guid(blobIdString);

        RoutineFragment routineFragment = new RoutineFragment(_blobId);
        SupportFragmentManager.BeginTransaction().Replace(Resource.Id.routine_frame, routineFragment).Commit();
    }
}

And the XML for this Activity:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/nothing"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000"
    android:orientation="vertical">

  <android.support.v7.widget.Toolbar
      android:id="@+id/doc_title_toolbar"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:background="?attr/colorPrimary"
      android:elevation="4dp"
      android:minHeight="?attr/actionBarSize"
      app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />

  <WebView
      android:id="@+id/routine_frame"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:transitionName="webview_preview_transition" />
</LinearLayout>

In my base theme, I do have <item name="android:windowContentTransitions">true</item>

I am at a loss what the issue might be. It seems like everything is set up right.

Answer 1

EDIT 02 Feb 2017: Xamarin developers have confirmed that it is a bug.

I was never able to get this working, but I suspect it might be a Xamarin bug. I found this bug on the AndroidSupportComponents issue tracker. Apparently it was found in rc1 of the support library but I do not see any developer response.