Since Wordpress 5.1 (or 5 in general) I have a problem with a cron job.

This cron top is filtering expired custom posts (coupon) and will mark it "not reliable" however its not working anymore. Unable to find the problem and need some help.

This the code:

 function clpr_coupon_prune() {
    global $clpr_options;

    $message = '';
    $links_list = '';
    $subject = __( 'Clipper Coupons Expired', APP_TD );

    if ( ! $clpr_options->prune_coupons ) {
        return;
    }

    // Get all coupons with an expired date that have expired
    $args = array(
        'post_type' => APP_POST_TYPE,
        'expired_coupons' => true,
        'posts_per_page' => -1,
        'fields' => 'ids',
        'no_found_rows' => true,
        'meta_query' => array(
            array(
                'key' => 'clpr_expire_date',
                'value' => '',
                'compare' => '!=',
            )
        )
    );
    $expired = new WP_Query( $args );

    if ( isset( $expired->posts ) && is_array( $expired->posts ) ) {
        foreach ( $expired->posts as $post_id ) {
            wp_update_post( array( 'ID' => $post_id, 'post_status' => 'draft' ) );
            $links_list .= html( 'li', get_permalink( $post_id ) ) . PHP_EOL;
        }
    }

    $message .= html( 'p', __( 'Your cron job has run successfully. ', APP_TD ) ) . PHP_EOL;
    if ( empty( $links_list ) ) {
        $message .= html( 'p', __( 'No expired coupons were found.', APP_TD ) ) . PHP_EOL;
    } else {
        $message .= html( 'p', __( 'The following coupons expired and have been taken down from your website: ', APP_TD ) ) . PHP_EOL;
        $message .= html( 'ul', $links_list ) . PHP_EOL;
    }

    $message .= html( 'p', __( 'Regards,', APP_TD ) . '<br />' . __( 'Clipper', APP_TD ) ) . PHP_EOL;

    if ( $clpr_options->prune_coupons_email ) {
        $email = array( 'to' => get_option( 'admin_email' ), 'subject' => $subject, 'message' => $message );
        $email = apply_filters( 'clpr_email_admin_coupons_expired', $email );

        appthemes_send_email( $email['to'], $email['subject'], $email['message'] );
    }
}
add_action( 'clpr_coupon_prune', 'clpr_coupon_prune' );


/**
 * Schedules a daily event to prune coupons which have expired.
 *
 * @return void
 */
function clpr_schedule_coupon_prune() {
    if ( ! wp_next_scheduled( 'clpr_coupon_prune' ) ) {
        wp_schedule_event( time(), 'daily', 'clpr_coupon_prune' );
    }
}
add_action( 'init', 'clpr_schedule_coupon_prune' );

Really would appreciate some help and some input how to fit this problem. Just cant understand why Wordpress 5.1 is not running the cron job!