Reported for: WPML Multilingual CMS 3.3.6
Resolved in: 4.2.5
The ‘Strip the category base (usually /category/) from the category URL.’ from Yoast SEO plugin does not work with WPML.
When you activate this option in Yoast SEO plugin (Strip the category base (usually /category/) from the category URL.), the categories in other language give 404 errors.
Disable that option in Yoast SEO plugin and use this plugin instead https://wordpress.org/plugins/no-category-base-wpml/