Sortable Event Date Column for Events

add_filter( 'manage_event_posts_columns', function ( $columns ) {
    $date = $columns['date'] ?? null;
    unset( $columns['date'] );
    $columns['event_start'] = 'Starts';
    $columns['event_venue'] = 'Venue';

    if ( $date ) {
        $columns['date'] = $date;
    }

    return $columns;
} );

add_action( 'manage_event_posts_custom_column', function ( $column, $post_id ) {
    if ( 'event_start' === $column ) {
        $date = date_create_immutable( (string) get_post_meta( $post_id, '_event_start', true ), wp_timezone() );
        echo $date && get_post_meta( $post_id, '_event_start', true ) ? esc_html( wp_date( get_option( 'date_format' ) . ' ' . get_option( 'time_format' ), $date->getTimestamp() ) ) : '—';
    } elseif ( 'event_venue' === $column ) {
        echo esc_html( get_post_meta( $post_id, '_event_venue', true ) ?: '—' );
    }
}, 10, 2 );

add_filter( 'manage_edit-event_sortable_columns', function ( $columns ) {
    $columns['event_start'] = 'event_start';

    return $columns;
} );

// Sort with a LEFT JOIN so events without a date stay in the list.
add_filter( 'posts_clauses', function ( $clauses, $query ) {
    global $wpdb;

    if ( ! is_admin() || ! $query->is_main_query() || 'event' !== $query->get( 'post_type' ) || ! in_array( $query->get( 'orderby' ), array( '', 'event_start' ), true ) ) {
        return $clauses;
    }

    $order = 'ASC' === strtoupper( (string) $query->get( 'order' ) ) ? 'ASC' : 'DESC';

    $clauses['join']   .= $wpdb->prepare( " LEFT JOIN {$wpdb->postmeta} AS wpide_ev ON ( wpide_ev.post_id = {$wpdb->posts}.ID AND wpide_ev.meta_key = %s )", '_event_start' );
    $clauses['orderby'] = "wpide_ev.meta_value {$order}, {$wpdb->posts}.post_date DESC";

    return $clauses;
}, 10, 2 );