I’m not sure why it’s hidden sometimes, but not others. I see the behavior on one of our servers, too. It’s confusing. Maybe it’s if no email address was specified during domain creation? That seems bug-like.
@Jamie@ilia why are we hiding the Contact email address field for some domains? (You can see it on virtualmin.com, even.)
Contact email doesn’t have to be sent to an email address in the domain! And, in cases where the domain doesn’t have email it obviously would not be in the domain, but they still almost certainly want to receive email about their domain.