Custom post type won't display, IS homepage & main query - wordpress

Question

I have a custom post type that worked just fine earlier, but not anymore. I haven't installed any new plugins and my code seems perfectly valid. Other custom fields are showing (default post type), but the ones I'm talking about not anymore.
Here's the code:
// Show posts of 'post', 'homepage_slider' post types on home page
add_action( 'pre_get_posts', 'add_my_post_types_to_query' );
function add_my_post_types_to_query( $query ) {
if ( is_home() && $query->is_main_query() )
$query->set( 'post_type', array( 'post', 'homepage_slider' ) );
return $query;
}
As you can guess, homepage_slider is my Custom Post Type. I haven't tweaked it's code one bit, but here it is just for reference:
function homepage_slider() {
$labels = array(
'name' => 'Images',
'singular_name' => 'Image',
'menu_name' => 'Homepage Slider Images',
'parent_item_colon' => 'Parent Image:',
'all_items' => 'All images',
'view_item' => 'View Image',
'add_new_item' => 'Add New Image',
'add_new' => 'Add New',
'edit_item' => 'Edit Image',
'update_item' => 'Update Image',
'search_items' => 'Search Image',
'not_found' => 'Not found',
'not_found_in_trash' => 'Not found in Trash',
);
$args = array(
'label' => 'homepage_slider',
'description' => 'Homepage Slider',
'labels' => $labels,
'supports' => array( 'title', 'thumbnail' ),
// 'taxonomies' => array( 'category', 'post_tag' ),
'hierarchical' => false,
'public' => true,
'show_ui' => true,
'show_in_menu' => true,
'show_in_nav_menus' => true,
'show_in_admin_bar' => true,
'menu_position' => 5,
'menu_icon' => 'myurl',
'can_export' => true,
'has_archive' => false,
'exclude_from_search' => true,
'publicly_queryable' => true,
'rewrite' => false,
'capability_type' => 'page',
);
register_post_type( 'homepage_slider', $args );
}
// Hook into the 'init' action
add_action( 'init', 'homepage_slider', 0 );
I have queried both the fact that it is indeed the homepage and the main query is indeed running. Really weird error.
Any suggestions?
EDIT: I think something's wrong with the add_my_post_types_to_query function as it's not working with another Custom Post Type either.

Answer 1

Try replacing:
function add_my_post_types_to_query( $query ) {
if ( is_home() && $query->is_main_query() )
$query->set( 'post_type', array( 'post', 'homepage_slider' ) );
return $query;
}
With:
function add_my_post_types_to_query( $query ) {
if ( $query->is_home() && $query->is_main_query() )
$query->set( 'post_type', array( 'post', 'homepage_slider' ) );
return $query;
}

Answer 2

Okay, so here's how I fixed it. Not quite a natural fix, but it did the job.
I simply created a new loop that runs through the custom post type wherever it must be placed and repeat for every other custom field I have on the homepage.
:)