Programmatically setting draft date not working

I’m using version 3.3.0 of PublishPress Future. I’m trying to programmatically set a post to draft when a post is created or updated, but no matter what date is set it seems to default to 7 days after the post published date. Do you know what I’m doing wrong?

function update_post_expiration($post_id, $post_after, $post_before)
{

        $application_deadline = get_post_meta( $post_id, 'application_deadline', true );

        $timestamp = strtotime( str_replace('-', '',$application_deadline) );
        $timestamp = strtotime('+1 day',$timestamp);
        $timestamp--;

        if (defined('PUBLISHPRESS_FUTURE_LOADED')) {
                do_action('publishpressfuture_unschedule_expiration', $post_id);
                $options   = [
                        'expireType' => 'draft',
                        'id'         => $post_id,
                ];
                do_action(
                        'publishpressfuture_schedule_expiration',
                        $post_id,
                        $timestamp,
                        $options
                );
        }

}
add_action('post_updated', 'update_post_expiration', 10, 3);