[Решено] Cart is being emptied when switching language

Background of the issue:
I am trying to maintain the cart contents when switching languages on my site скрытая ссылка. I have set the multicurrency settings to sync the cart when the language or currency changes. All products are duplicated from the default language.

Symptoms:
When I switch language and items are in the cart, the cart empties.

Questions:
Why does the cart empty when switching languages despite having set the multicurrency settings to sync?
Is there a specific setting in WPML that I might be missing to prevent the cart from emptying?