Adding tab to user/uid page - weird behavior

I have successfully created a page view that places a tab on the main user profile page (at user/uid). To create the tab, I set the path and menu as follows:

Path: user/%/amigos
Menu: Type = "Menu tab", Title = "Amigos"

So when I navigate for example to user/10, I see the users main profile page with the following tab structure:

View|Amigos|Edit|Track etc.

If I click on the "Amigos" tab, I am taken to (for example) user/10/amigos, where I see that the contents of the view show correctly.

The PROBLEM is that once I'm one the page with the view, all the tabs have disappeared, and the page title as well. What I would expect is for the title and tabs to remain in place, providing a seamless user profile navigation experience.
You can see the export of my view below in case it is a configuration problem. If it is not a configuration problem, could someone tell me whether this is a bug or if it is working as designed? Any help in getting the other pre-existing tabs to remain in place while viewing the tab provided by my view would be greatly appreciated.

thanks!

$view = new view;
$view->name = 'Amigos_x_perfil';
$view->description = 'Ver todos los amigos del miembro cuyo perfil se está viendo';
$view->tag = '';
$view->view_php = '';
$view->base_table = 'user_relationships';
$view->is_cacheable = FALSE;
$view->api_version = 2;
$view->disabled = FALSE; /* Edit this to true to make a default view disabled initially */
$handler = $view->new_display('default', 'Defaults', 'default');
$handler->override_option('relationships', array(
  'requestee_id' => array(
    'id' => 'requestee_id',
    'table' => 'user_relationships',
    'field' => 'requestee_id',
  ),
));
$handler->override_option('fields', array(
  'picture' => array(
    'label' => '',
    'alter' => array(
      'alter_text' => 0,
      'text' => '',
      'make_link' => 0,
      'path' => '',
      'link_class' => '',
      'alt' => '',
      'prefix' => '',
      'suffix' => '',
      'help' => '',
      'trim' => 0,
      'max_length' => '',
      'word_boundary' => 1,
      'ellipsis' => 1,
      'strip_tags' => 0,
      'html' => 0,
    ),
    'exclude' => 0,
    'id' => 'picture',
    'table' => 'users',
    'field' => 'picture',
    'relationship' => 'requestee_id',
  ),
  'name' => array(
    'label' => '',
    'alter' => array(
      'alter_text' => 0,
      'text' => '',
      'make_link' => 0,
      'path' => '',
      'link_class' => '',
      'alt' => '',
      'prefix' => '',
      'suffix' => '',
      'help' => '',
      'trim' => 1,
      'max_length' => '6',
      'word_boundary' => 0,
      'ellipsis' => 1,
      'strip_tags' => 0,
      'html' => 0,
    ),
    'link_to_user' => 0,
    'overwrite_anonymous' => 0,
    'anonymous_text' => '',
    'exclude' => 0,
    'id' => 'name',
    'table' => 'users',
    'field' => 'name',
    'relationship' => 'requestee_id',
  ),
));
$handler->override_option('arguments', array(
  'requester_id' => array(
    'default_action' => 'not found',
    'style_plugin' => 'default_summary',
    'style_options' => array(),
    'wildcard' => '',
    'wildcard_substitution' => '',
    'title' => '',
    'breadcrumb' => '',
    'default_argument_type' => 'fixed',
    'default_argument' => '',
    'validate_type' => 'numeric',
    'validate_fail' => 'not found',
    'break_phrase' => 0,
    'not' => 0,
    'id' => 'requester_id',
    'table' => 'user_relationships',
    'field' => 'requester_id',
    'validate_user_argument_type' => 'uid',
    'validate_user_roles' => array(
      '2' => 0,
      '3' => 0,
      '5' => 0,
      '4' => 0,
    ),
    'override' => array(
      'button' => 'Override',
    ),
    'relationship' => 'none',
    'default_options_div_prefix' => '',
    'default_argument_user' => 0,
    'default_argument_fixed' => '',
    'validate_argument_node_type' => array(
      'blog' => 0,
      'poll' => 0,
      'image' => 0,
      'forum' => 0,
      'book' => 0,
      'centro_edu' => 0,
      'chat' => 0,
      'estudios' => 0,
      'page' => 0,
      'perfiles_profesionales' => 0,
      'profile' => 0,
      'story' => 0,
      'yaq_breve' => 0,
    ),
    'validate_argument_node_access' => 0,
    'validate_argument_nid_type' => 'nid',
    'validate_argument_vocabulary' => array(
      '8' => 0,
      '3' => 0,
      '7' => 0,
      '9' => 0,
      '11' => 0,
      '5' => 0,
      '10' => 0,
      '12' => 0,
      '1' => 0,
      '6' => 0,
      '4' => 0,
    ),
    'validate_argument_type' => 'tid',
    'validate_argument_transform' => 0,
    'validate_user_restrict_roles' => 0,
    'validate_argument_node_flag_name' => '*relationship*',
    'validate_argument_node_flag_test' => 'flaggable',
    'validate_argument_node_flag_id_type' => 'id',
    'validate_argument_user_flag_name' => '*relationship*',
    'validate_argument_user_flag_test' => 'flaggable',
    'validate_argument_user_flag_id_type' => 'id',
    'image_size' => array(
      '_original' => '_original',
      'thumbnail' => 'thumbnail',
      'preview' => 'preview',
      'tiny' => 'tiny',
    ),
    'default_argument_php' => '',
    'validate_argument_php' => '',
  ),
));
$handler->override_option('filters', array(
  'status' => array(
    'operator' => '=',
    'value' => '1',
    'group' => '0',
    'exposed' => FALSE,
    'expose' => array(
      'operator' => FALSE,
      'label' => '',
    ),
    'id' => 'status',
    'table' => 'users',
    'field' => 'status',
    'relationship' => 'requestee_id',
    'override' => array(
      'button' => 'Override',
    ),
  ),
  'rtype' => array(
    'operator' => 'in',
    'value' => array(
      '0' => '1',
    ),
    'group' => '0',
    'exposed' => FALSE,
    'expose' => array(
      'operator' => FALSE,
      'label' => '',
    ),
    'id' => 'rtype',
    'table' => 'user_relationships',
    'field' => 'rtype',
    'override' => array(
      'button' => 'Override',
    ),
    'relationship' => 'none',
  ),
));
$handler->override_option('access', array(
  'type' => 'none',
));
$handler->override_option('cache', array(
  'type' => 'none',
));
$handler->override_option('empty', 'Este usuario todavía no ha añadido ningún amigo');
$handler->override_option('empty_format', '4');
$handler->override_option('items_per_page', 30);
$handler->override_option('use_pager', '1');
$handler = $view->new_display('page', 'Página', 'page_1');
$handler->override_option('path', 'user/%/amigos');
$handler->override_option('menu', array(
  'type' => 'tab',
  'title' => 'Amigos',
  'description' => 'Ver los amigos de este miembro',
  'weight' => '0',
  'name' => 'navigation',
));
$handler->override_option('tab_options', array(
  'type' => 'none',
  'title' => '',
  'description' => '',
  'weight' => '0',
));
$handler = $view->new_display('block', 'Bloque', 'block_1');
$handler->override_option('block_description', '');
$handler->override_option('block_caching', -1);