[Cerrado] The NL pages does not show when selected

Background of the issue:
I am trying to set up a multilingual website with three languages activated: English, German, and Dutch. When I navigate to the homepage in each language and click the respective 'Book Now' button, I expect to see the page in the selected language. The issue can be seen on the page: enlace oculto. I expected to see the Dutch page at enlace oculto.

Symptoms:
When I go to the homepage in Dutch and click on the button 'Boek nu', it shows the English page instead of the Dutch page. Instead of the expected Dutch page, I got: enlace oculto.

Questions:
Why does the Dutch 'Boek nu' button lead to the English page instead of the Dutch page?
How can I ensure the Dutch page is displayed correctly when the 'Boek nu' button is clicked?