[@robkk Moderator 11 years, 2 months ago]

You might have removed/there isn’t a certain piece of code that renders the classes for each topic/reply.

You might be missing this in loop-single-reply.php in your custom templates that you placed in your child theme.

<?php bbp_reply_class(); ?>

Maybe this for topics too in loop-single-topic.php

<?php bbp_topic_class(); ?>