Julien Arauzo

Problem:
The client is experiencing an issue with WPML where the product category menu incorrectly adds a language prefix (e.g., '/de/') to URLs in the default language (French). This problem reoccurs even after clearing the cache.
Solution:
We identified that the issue affects only the navigation menu items. As a temporary workaround, we recommended excluding certain persistent groups by adding them to an MU plugin. Here is the code snippet to use:

// Additional groups to test<br />    'terms',<br />    'term_meta',<br />    'nav_menu',<br />    'nav_menu_item',<br />    'woocommerce',<br />    'product_cat',

For a more permanent solution, we escalated the issue to our developers and required a copy of the site and FTP access to investigate further. Additionally, we implemented several changes on the live site:
1. Added more URL-related filters to the MU plugin.
2. Enabled the debug log in the wp-config.php file.
3. Added a new tracking MU plugin named wsupp-menu-debug.php to log any occurrences of the issue.
We will monitor the site and have asked the client to notify us if the issue reappears.

If this solution does not resolve your issue or seems outdated, we recommend checking the related known issues, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If the problem persists, please open a new support ticket.