I'm working on a shop site. I'm trying to use the feature "page overlay" as a way to show the size chart. In this example product: https://massafeina.com/product/producte-001/ the overlay page (size chart) would appear after clicking on GUIA DE TALLES link (in the product description). However the page opens as a normal page instead of an overlay page.

On the contrary, here: https://massafeina.com/pagina-prova/ I set this grey square as a link to this page and it does open as an overlay page.

Is there a way I could make the page open as an overlay page even when the link is inside a page I created under pages but a product page created by woocommerce?

Thank you very much.

Eduard