Sorry my delay.
Example of an order that was abandoned before finishing the payment process:
https://snipboard.io/gmGrCW.jpg
It displays the extra field ok.
Example of an order that was paid normally with credit card
https://snipboard.io/te36k5.jpg
No extra field.
Please keep in mind that the extra field ‘Solicitar factura’ is a html <select> that has only two options: ‘No’ (default) and ‘Si’. So it is not possible to leave it blank. It always has a value.