WooCommerce enable Reviews for all products
With WooCommerce, there is an option to enable/disable reviews for each product.
Unfortunately, the checkbox doesn’t come checked by default. This box being checked depends on whether or not you have comments enabled in Settings > Discussion.
This would potentially mean that you would have to browse through each of the 3000+ products and check off the box manually.
How to enable Reviews for all products in WooCommerce
If you have database access just run this query :
UPDATE wp_posts SET comment_status = "open" ;
(you can install the DB Manager plugin and run this query also)