[v1.6.1.18] VAT_number field disappear when selecting certain countries in new address menu

[Nandos]

Like the title, when i go to the Back Office -> Customers -> Addresses, and i try to add a new address, in this case of a company, when i reach the point where i have to select the country and i pick one, the vat number just disappaer. The store is italian and in this case i'm selecting san marino as country for this new address.

 

Any hint? It works for other countries like cipro, uk, etc... can't figure out this one, i need help.

Edited April 5, 2018 by Nandos (see edit history)