get_posts() function does not honor correct post type

Question

I'm fetching all posts of a specific custom post type like below.

print_r(ANCR_POST_TYPE);

$announcements = array();
$announcement_posts = get_posts(array(
    'post_type' => ANCR_POST_TYPE, // Post type is set to "announcer"
    'posts_per_page' => 2,
    'orderby' => 'menu_order',
    'order' => 'asc',
    'post_status' => 'publish'
));

print_r($announcement_posts);

But the get_posts() function returns posts which are not of type ANCR_POST_TYPE

announcer
Array
    (
        [0] => WP_Post Object
            (
                [ID] => 104
                [post_author] => 1
                [post_date] => 2023-07-07 18:15:23
                [post_date_gmt] => 2023-07-07 18:15:23
                [post_content] => This is an event
                [post_title] => Event
                [post_excerpt] => 
                [post_status] => publish
                [comment_status] => open
                [ping_status] => closed
                [post_password] => 
                [post_name] => event
                [to_ping] => 
                [pinged] => 
                [post_modified] => 2023-07-07 18:15:23
                [post_modified_gmt] => 2023-07-07 18:15:23
                [post_content_filtered] => 
                [post_parent] => 0
                [guid] => https://example.com/?post_type=tribe_events&p=104
                [menu_order] => 0
                [post_type] => tribe_events  <----- posts of type "tribe_events" is retreived instead of type "announcer"
                [post_mime_type] => 
                [comment_count] => 0
                [filter] => raw
            )
    
    )

This is seen only on the tags archive page of "tribe_events" post type.

Any idea on when this could happen?

Answer 1

This could be caused by a pre_get_posts action that doesn't have the proper conditions/checks.

For example:

add_action( 'pre_get_posts', function( $query ) : void {
    if ( is_post_type_archive( 'tribe_events' ) ) {
        $query->set( 'post_type', 'tribe_events' );
    }
} );

Likewise if this was a page template and not a post archive they might have this in their theme template to force it to show only posts of that type:

add_action( 'pre_get_posts', function( $query ) : void {
    $query->set( 'post_type', 'tribe_events' );
} );

Both of these would cause the problem you described. Fixing them will be specific to that specific callback though.Checking $query->is_main_query() may help.

How to Fix It?

Fundamentally this isn't a problem with your plugin, it's something in the users site code, and they will need to find and identify this. The usual process of elimination of disabling things and checking will help, as will a search and code review of any pre_get_posts callbacks.