modifying meta_query on parse_query

In the parse_query filter hook I’m doing:

if ( is_admin() && $pagenow == 'edit.php' && isset( $_GET['ysr_homepage_filter'] ) && $_GET['ysr_homepage_filter'] == '1' ) {
        if ( ! $query->meta_query ) {
            $query->meta_query = new WP_Meta_Query( [
                [
                    'key'     => 'ysr_home_sticky',
                    'value'   => '1',
                    'compare' => '='
                ]
            ] );
        }
    }

to try to filter by a particular meta in the dashboard listing for a particular custom post type.

The custom field is the correct one, and I’m searching succesfully for it in other WP_Queries, but apparently what I’m doing here is not the proper way to do things, since my results remain unaffected. Code run throuh there properly, and I can see that $query->meta_query is set to my new WP_Meta_Query, but it doesn’t seem to matter.

Any clues on what I’m doing wrong? Is there a different hook should I be hooking into? A different way to create the new meta query for the existing query object?

Thanks in advance.