WooCommerce Product Add On - all global add-on labels display the first option label

Overview of the issue

On the front-end, all global Add-on labels display the first option label. They should display the correct option labels.

You can see an example of the issue in the following screenshot. 

Workaround

In the ../woocommerce-multilingual/compatibility/class-wcml-product-addons.php file, change this line

                     $addons[ $key ][ 'options' ][ $opt_key ][ 'label' ] = apply_filters( 'wpml_translate_single_string', $option['label'], 'wc_product_addons_strings', $object_id . '_addon_' . $addon['type'] . '_' . $addon['position'] . '_option_label_' . $key );

to:

                     $addons[ $key ][ 'options' ][ $opt_key ][ 'label' ] = apply_filters( 'wpml_translate_single_string', $option['label'], 'wc_product_addons_strings', $object_id . '_addon_' . $addon['type'] . '_' . $addon['position'] . '_option_label_' . $opt_key );

This workaround will be applied in the next, 3.8.3 release of WooCommerce Multilingual.