Custom form Media Library Browser disappears after image upload within CTools content type dialog

(I've tried this with multiple releases, including 1.6, and the issue remains).

I have a custom CTools content type (plugin), which is to be output in a panel layout being used for the homepage. The plugin configuration is using several custom form elements, all of which work fine aside from one, which is of '#type' => 'media'.

The media dialog opens over the CTools dialog (great), and I'm able to save/upload an image after going through the media upload wizard with the file being saved in the database. The Media dialog then closes, then the image's thumbnail is visible within the field as it should. However, within a second or so, a throbber appears next to the field, followed by the field disappearing all together and being replaced with: ''.

I'm assuming that this is indeed an issue with the CTools dialog, rather than the Media module. For reference, the form field's definition is below:

 $form['welcome_block_hero_image'] = array(
    '#type' => 'media',
    '#tree' => TRUE,
    '#title' => t('Hero Image'),
    '#description' => t('Allowed formats: PNG, JPG, JPEG, GIF.'),
    '#media_options' => array(
      'global' => array(
        'file_extensions' => 'png jpg jpeg gif',
        'max_filesize' => '10 MB',
        'types' => array('image'),
      ),
    ),
    '#required' => TRUE,
  );

Any info here would be great.

Thanks in advance,

Adam