This thread is resolved. Here is a description of the problem and solution.
Problem: I am trying to: logout on ENGLISH version of my website. (the PORTUGUESE version is working fine)
Solution: I kindly ask you to follow this steps: - Go to this link: https://sensetemplates.com/wp-admin/admin.php?page=wpml-string-translation%2Fmenu%2Fstring-translation.php&search=customer-logout&search_translation=1 -> Translate the Endpoint and the Menus (Make sure that the 'Translation is complete' option is selected).
This is the technical support forum for WPML - the multilingual WordPress plugin.