This thread is resolved. Here is a description of the problem and solution.
Problem: The attribute selection placeholder on the produdt pages is not translated.
Solution: Go to WooCommerce -> WooCommerce Multilingual and select the "Status" tab. You should find in the right bottom corner a link for the Troubleshooting options. Here please sync all the available content, also take note that you will find more options in the drop down for "Duplicate terms".
If this will not solve the issue it is theme related.
Relevant Documentation: https://wpml.org/documentation/related-projects/woocommerce-multilingual/
This is the technical support forum for WPML - the multilingual WordPress plugin.