[Resolvido] wp menu sync issue: menu synchronization not working

Background of the issue:
I am trying to synchronize the menu for my site, which has two languages: English and Dutch. The site URL is link oculto.

Symptoms:
Menu synchronization is not working, and I can't get the menu translated, making the Dutch version of the site inaccessible.

Questions:
Why is the menu synchronization not working for the Dutch version of my site?