Variable products default selection is not copied to translations.

Created products in the default language (EN), all with a default variations.
Then created the translated versions of those products, and all default variations are locked to: “no default”.

This issue happens to Latvian language. Russian and English (default) are OK

Site – http://www.granulas.eu
Product – http://www.granulas.eu/lv/product/gaisas-granulas-extra/

https://wordpress.org/plugins/woocommerce/