Hi @customcv, Try to add the card from a different computer or device and use another Internet connection, If still this not resolve the issue then contact the Woo customer support by open the support ticket.
The issue is fixed by downgrading the version of WooCommerce PayPal Payments from v2.7.1 into v2.7.0 the PayPal plugin yesterday updated automatically which fixed an issue of their plugin and that is what is conflicting with the WooCommerce Shipping Labels.
Issue: “Fixed – Ensure package tracking data is sent to original PayPal transaction” this fixed is issued of WooCommerce PayPal Payments Plugin which conflicts with WooCommerce Shipping Labels.