Please try this:
$args = array(
'number' => 100,
'status' => 'approve',
'post_status' => 'publish',
'post_type' => 'product'
);
$comments = get_comments( $args );
where you can edit the number of comments to your needs.
Debug:
Maybe something is changing it via the pre_get_comments hook?
To debug it you can check out the SQL query with:
global $wpdb;
printf( '<pre>%s</pre>', $wpdb->last_query );
where you add this directly below the above get_comments() code snippet.
Also check the edit-comments.php screen if the comments show up there and their status.