List-Unsubscribe

When we checked the Gmail “Show Original”, we see that the List-Unsubscribe header is in the original newsletter. However, when the email is opened there is no “unsubscribe” link shown after the sender’s email like most other newsletters in Gmail.

When you click on the down arrow on the “to” email”, Gmail will show a list, one of which is “unsubscribe: Unsubscribe from this sender”. But the mails send from Newsletter does NOT have this line shown in Gmail. Why is that?