Hi a.gryger,
Thanks for reaching to us.
Try to regenerate Regenerate the product attributes lookup table
in Woocommerce > Status > Tools https://take.ms/LGpvf
In addition, please check Woocommerce > Settings > Product tab > Advanced tab and disable Use the product attributes lookup table for catalog filtering
.
You need to add the widgets to the Shop page widget area: https://xtemos.com/docs-topic/widgets-and-sidebars/
As soon as you create the categories and attributes they would be reflected in the list of the widget.
Kind Regards,