I discovered that (replies) pagination printed inside each topic on topic list does not work if the replies counts more than 1000 entries. This is due to the use of
$total = bbp_get_topic_reply_count( $topic_id );
on bb-topic-template.php. The total from bbp_get_topic_reply_count is returned as a formatted number, for example 1,449 and passing this value to the core WordPress paginate_links() from general-template.php leads to empty page list.
The bbp_get_topic_reply_count() should accept a second parameter to stop the formatting.