First, I don't use WPML for a multilingual website, so I use no strings at all for the homepage.
I also updated WPML Multilingual CMS to the latest version.
Second, When I deactivate String translation plugin, the problem stell remains.
In your first statement your said "You're right. It comes from WPML. When I deactivate WPML, the problem is solved.
But I need that plugin for string translations."
Here you're stating that once WPML is disabled then the issue is no longer present .
Now you're stating below. First, I don't use WPML for a multilingual website, so I use no strings at all for the homepage.
I also updated WPML Multilingual CMS to the latest version.
Second, When I deactivate String translation plugin, the problem stell remains.
Which gives me the impression that you're not using WPML, however the site is using WPML
When I checked the page again today I can see that the conditionals are now working. See Screenshot.
The article on the right is now displaying the taxonomy.