How to add meta boxes for custom post types with Wordpress gutenberg

Question

I'm trying to register a metabox for some custom post types. Currently, I'm using the add_meta_box function with the screen parameter set to the post type slug:

    $post_types = ['post', 'page', 'cms_pim_profile', 'cms_resource_hub', 'cms_stories', 'cms_opportunities', 'cms_events'];
    foreach ( $post_types as $post_type )
    {
        add_meta_box(
            'cms2019-sticky-until-' . $post_type,
            'Sticky',
            'cms2019_sticky_until',
            $post_type,
            'side',
            'high'
        );
    }

The problem is that the metabox simply does not appear for posts - the custom post types and the default 'post'. It does, however, correctly appear for pages, so I know the display/save functions are working correctly.

Is there something else I need to do for posts?

Answer 1

You need to add a action-hook.

For the meta-box it´s called:

add_action('add_meta_boxes', 'your_function_name');

function your_function_name() {

    add_meta_box(...);

}