Shannon W on "[Plugin: WooCommerce] Add reviews gone missing"

I haven't touched this site in months and if someone else has, I have no idea what they've done BUT ....

If there is an existing review on a product, then the Reviews tab shows as expected and within the tab, the review details are displayed PLUS the "Add a Review" textarea box and submit button - all good
e.g. https://www.janomesewingcentre.com.au/shop/sewing-machines/janome-dc6050/

Problem:
If there is 0 reviews, then nothing is displayed (the "Add a Review" section no longer displays)
e.g. https://www.janomesewingcentre.com.au/shop/sewing-machines/janome-dc3100/
Looking at the code, the entire div (below) has disappeared.

<div class="product_single_description" id="tab-review">

On pages where reviews exist, this div appears, where no reviews exist, this div disappears.

I have checked my override file

/wp-content/themes/mytheme/woocommerce/single-product/tabs/tabs.php

and the review tab is displayed or hidden based on:

$tabs = apply_filters( 'woocommerce_product_tabs', array() );
if ( ! empty( $tabs ) ) :

Therefore - it would appear that the "add a review" content is not being populated if no review exists...

That's about the extent of my detective work and I don't know where to go from here...

Anyone have any idea where I should be looking for this one?

- I have checked the product and "Allow Idea" is true
- I have checked functions.php and no filter is removing reviews

NOTE: The same is also true for the additional description tab

Help

https://wordpress.org/plugins/woocommerce/