HTML sitemap does not show

Hello everyone

I embedded [wp_sitemap_page] into the page at the URL as shown in the field and published the page. However, no HTML sitemap appears.

I suspect the problem is due to the custom theme installed on the site, but cannot work out what the theme lacks. Could someone please tell me what can make the HTML sitemap not appear with this plugin?

Thank you in advance,

Ead

The page I need help with: [log in to see the link]