This thread is resolved. Here is a description of the problem and solution.
The portfolio featured images are missing in the secondary languages.
It happens when you forget to check the option 'Duplicate featured images to translations' in the post editing screen. When it happens it is possible to bulk duplicate the featured images to translation this way:
1 - Go to your WordPress Dashboard > WPML > Settings > Media Translation make sure all the options are checked and click the blue 'start' button.
2 - Wait the whole process and you should be done.
This is the technical support forum for WPML - the multilingual WordPress plugin.
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