Standard Tax class not displayed for Product Fees taxes

With WooCommerce Product Fees version 1.2, in Woocommerce settings -> Products -> Products Fees, in front of Fee Tax Classes, we find the dropdown menu with the “no taxes fo fess” first and then the list of the tax classes we have added. However, the Standard Tax class, the one created by default by Woocommerce, does not appear in this menu.
I find this bug with the 2 different shops (with different plugins) I am managing.

https://wordpress.org/plugins/woocommerce-product-fees/