Not sure if it's a bug or the expected behavior, selecting single opt-out for a list, I still see the unsubscribe form asking for confirmation when I click an unsubscribe link (i.e [UNSUBSCRIBE_URL]) in a campaign email.
After cleaning the cache/cookies/storages of my browsers (tried in Chrome and Firefox yesterday), the issue is gone... So, it was just a local one Maybe because I tested with double opt-out previously (earlier or the previous day, don't remember)...