localization persistance

Hello,
I am having an issue with a Woocommerce translation being overwritten.

What I’ve tried so far:
– moving my woocommerce-de_DE.po/mo files to wp-content/languages/plugins/
– blocking translation auto-updates with add_filter( ‘auto_update_translation’, ‘__return_false’ );
– setting the po/mo files permissions to 444
None of those worked, and I am having troubles identifying the cause of the problem.

Do you have any suggestions?
Cheers
Chiara

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