[Risolto] Wpml keeps displaying message translation is not complete but it says 100% in bottom

Background of the issue:
I am trying to translate products in WooCommerce using WPML on my site. I am using the Advanced Translation Editor (ATE) for this task.

Symptoms:
WPML keeps displaying the message "In order to declare this as complete, ...." even though the progress shows 100% at the bottom. It won't save the translation as complete.

Video: link nascosto

Questions:
Why does WPML show 'translation is not complete' when the progress is 100%?
How can I save the translation as complete in WPML?