Buddypress follow conflict

The problem with the plugin is it is querying for posts on the 'pre_get_posts' hook, so this means that this plugin will run code that runs on the main post hooks twice.

Since it looks like this plugin is only meant to be looking for already-queried posts, I would recommend rewriting the mark_posts_as_read() method to the following:

public function mark_posts_as_read($posts, $query) {
    $headers = function_exists('getallheaders') ? getallheaders() : $this->get_headers();
    if ($headers && isset($headers['X-Moz']) && $headers['X-Moz'] === 'prefetch') return $posts;
    if ($this->posts_marked || $this->is_special_page() || ! $query->is_main_query()) return $posts;
    $this->posts_marked = true;
    $read_posts_ids = $this->get_read_posts_ids();
    $update_cookie = false;
    foreach ($posts as $post) {
        $post_id = $post->ID;
        if ($this->is_after_cookie_time($post) && !in_array($post_id, $read_posts_ids) || $this->is_test) {
            $this->new_posts_displayed = true;
            if ($this->options->mark_after !== MarkNewPosts_MarkAfter::OPENING_POST || is_single()) {
                $read_posts_ids[] = $post_id;
                $update_cookie = true;
            }
        }
    }
    if (!$update_cookie) return $posts;
    array_unshift($read_posts_ids, $this->last_visit);
    $this->set_cookie(join(self::COOKIE_DELIMITER, $read_posts_ids));
    return $posts;
}

Then change your hook from 'pre_get_posts' to 'the_posts':

add_filter('the_posts', array(&$this, 'mark_posts_as_read'), 10, 2);

I’m not 100% sure if this will break certain parts of your plugin, but hopefully it gives you an idea of where to optimize your code.

Thank you! I’ll try to look into it as soon as I can.

The change suggested by @r-a-y is something that I should’ve been doing from the start. I tested it, and it seems to work perfectly fine. New version’s out. Thanks, Ray and @teeboy4real !