Cannot leave reviews

We have reviews in our shop, so it used to work but now I cannot leave reviews, e.g. https://www.salesessentials.com/shop/barrett-whitepaper-the-history-of-sales-methodologies-why-some-work-and-others-dont/

In the dashboard I have “Enable ratings on reviews” turned on, and I
tried various different configurations of the other four, still does not work. Also “allow comments” in the product section is turned on.

I have no idea when the reviews stopped … so I cannot comment on that.

Any ideas how I can solve this?
where is this in the code and db?

Jobst

https://www.ads-software.com/plugins/woocommerce/