You shouldn’t need to have a plugin for these to show. They’ve always shown up in the past, but something has changed in the one of the most recent Woocommerce versions, so now any reviews that you enter manually don’t show.
eg: https://chrisgarlandtraining.co.uk/courses/evacuation-sledge-training/
(I picked this one for simplicity)
I’ve also just raised it with WooCommerce directly as this is going to cause me big problems as I collect candidate feedback a the end of each course. This is then uploaded. If 12 candidates leave feedback, but their manager is the one who gets the feedback request email, it means that I’ve got a problem!