Activate ratings for all products programmatically with the following code:
add_action('admin_init', 'iphf_enable_reviews');
function iphf_enable_reviews() {
$args = array(
'post_type' => 'product',
'numberposts' => -1,
'comment_status' => 'closed',
'post_status' => 'publish',
);
$shop_products = get_posts( $args );
foreach( $shop_products as $item){
$product = new WC_Product($item->ID);
wp_update_post( array(
'ID' => $item->ID,
'comment_status' => 'open',
) );
}
}
Paste this code into functions.php or use it as a plugin and open the admin panel once. After that, all products should have ratings (reviews) enabled. The code can then be removed again.