Anja

Problem:
During checkout payment gateways are displayed even when the total amount is 0 (only free products in the cart). In this case the problem was due to a conflict with the WooCommerce Amazon Pay plugin.

Solution:
We have identified a conflict between WooCommerce Multilingual (WCML) and the WooCommerce Amazon Pay plugin. As a temporary workaround, you can edit the WooCommerce Amazon Pay plugin code. Here are the steps:

1. Navigate to the file

wp-content/plugins/woocommerce-gateway-amazon-payments-advanced/includes/compats/class-wc-amazon-payments-advanced-woocommerce-multilingual-compat.php

.
2. Locate the function

maybe_restore_subtotal

around line 22.
3. Replace the existing code of that function with the following:

public function maybe_restore_subtotal( $cart ) {
	if ( ! class_exists( 'woocommerce_wpml' ) ) {
		return;
	}

	if ( ! defined( 'WC_DOING_AJAX' ) || ! WC_DOING_AJAX ) {
		return;
	}

	if ( WC()->cart->total == 0) {
		return;
	}

	// WCML sets cart->needs_payment() to become `false`.
	add_filter( 'woocommerce_cart_needs_payment', '__return_true' );
}

We will also contact the plugin authors to incorporate this solution. Meanwhile, you can encourage them to join the WPML Go Global program.