Hello,
When I clear WooCommerce transients and Regenerate the product attributes lookup table from this page https://ma****er.com/wp-admin/admin.php?page=wc-status&tab=tools , the filter works fine on both languages for a while, then it back to the current behavior.
As we said there is some conflict in plugins, we are sure that the situation is independent of the theme, because the default WooCommerce widget, this one – https://prnt.sc/mZhOQ3cXG1FR is displayed in only 1 language, which means it doesn’t work correctly also. The functionality of our and the default WC widgets is similar, so you need to fix the problem with the default widget first. Likely after that our widget starts working also.
Please contact the support of WooCommerce and WPML, ask for their help in solving the problem with the “Filter Products by Attribute” default WC widget.
Let us know once it will be solved/results.
Regards