Hello @eszdan ,
thank you for your question.
First of all, I would check that the setting in Administration -> menu Packeta -> submenu Settings -> tab General -> Payment method that represents cash on delivery is filled in with appropriate payment method.
If it is, I would check that all other options of Packeta plugin and Woocommerce are configured correctly according to the User manual available at Github Wiki page https://github.com/Zasilkovna/WooCommerce/wiki/User-documentation-(EN)
If neither of this helps you to solve the problem, please do reach us via e-mail technicka.podpora@zasilkovna.cz . Together we can solve your issue more quickly, if you attach Export of Packeta plugin settings, which you can get from Administration -> menu Packeta -> submenu Settings -> tab Support -> button Export the plugin settings.
Regards,
Oldrich Mraz – Packeta E-shop Solutions
@mrakorcz Thank you for your help, we managed to find what was missing (the setting).
Thanks again!