How to make Comment Review option work in any theme
If you're using WP Product Review and the user comment review option is still not appearing after activating it, then it's probably an issue with your theme's comments.php file. It usually happens when theme developers use custom comment form templates.
It could be solved by adding the following snippet to just above the textbox code in your comments.php file:
<?php do_action('comment_form_after_fields'); ?>
You might wanna inform your theme developer about this. :)