Unable to display the VAT number

Hello, I have a problem in customizing my bill. I have an eshop divided into two parts, one part for classic customers and one part for professional customers with a VAT number. There is therefore in the registration and validation of order a field VAT number not required. I need that when this field is filled, the customer’s VAT number is found in the invoice. I see in the custom of the invoice that there is the possibility to add a VAT number but the section is greyed out and impossible to activate it. https://ibb.co/xztrFbq

How can I display the VAT number in invoices?

My configuration

WordPress 6.4

woocommerce 8.2.1

EU/UK VAT for WooCommerce 2.9.13 to retrieve the VAT number of customers

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