Example of how to remove the post_where filter used in the Royal Event theme which prevents the use of custom post statuses.

tw_ee_remove_royal_event_query_posts_where.php

<?php //Please do not include the opening PHP tag if you already have one.

add_filter( 'posts_where', 'tw_ee_remove_royal_event_query_posts_where', 9, 2 );
function tw_ee_remove_royal_event_query_posts_where($where, $query) {
    if( $query->query_vars['post_type'] == 'espresso_events' ) {
        remove_filter( 'posts_where', 'royal_event_query_posts_where' );
    }
    return $where;
}