Latest AIO update broke something with FB Frontend Submission

I just updated my AIO and now when editing an existing post via MB Frontend Submission, the post_title and post_content fields no longer populate with the existing data. It worked fine before the update. I have to use custom meta boxes, instead of the "post_fields" attribute in the shortcode, because I need more control over headings and placement on the form.

Additionally, the thumbnail upload only works when using "post_fields". I can't get it to work when using a defined meta box.

Here is my code:

$meta_boxes[] = array (
     'title'  => 'Event Name',
     'id' => 'event-title',
     'fields' => array(
          array (
               'id' => 'heading_title',
               'type' => 'heading',
               'desc' => 'What is the name of your event?',
               'name' => 'Event Name',
          ),
          array(
               'name'     => 'Event Name',
               'id'       => 'post_title',
               'type'     => 'text',
               'required' => true,
          ),
     ),
);

$meta_boxes[] = array (
     'title'  => 'Event Description',
     'id' => 'event-desc',
     'fields' => array(
          array (
               'id' => 'heading_desc',
               'type' => 'heading',
               'desc' => 'Please provide some information about this event. The more detailed, the better.',
               'name' => 'Event Description',
          ),
          array(
               'name' => 'Event Description',
               'id' => 'post_content',
               'type' => 'wysiwyg',
               'raw' => false,

               // Editor settings
               'options' => array(
                    'textarea_rows' => 20,
                    'teeny' => true,
               ),
               'required' => true,
          ),
     ),
);

$meta_boxes[] = array (
     'title'  => 'Cover Image',
     'id' => 'event-cover',
     'fields' => array(
          array (
               'id' => 'heading_title',
               'type' => 'heading',
               'desc' => 'The cover image is the large photo that appears at the top of your listing. For the best results, use an image measuring 1920x823 pixels (21:9 aspect ratio). The cover image is optional.',
               'name' => 'Cover Image',
          ),
          array(
               'type' => current_user_can( 'upload_files' ) ? 'single_image' : 'image',
               'name' => 'Cover Image',
               'id' => '_thumbnail_id',
               'max_file_uploads' => 1,
               'force_delete' => true,
          ),
     ),
);