For some reason the rss feed to campaign stopped parsing the feed and after contacting Mailchimp support they indicated me that the current feed is not valid according to this:
https://validator.w3.org/feed/check.cgi?url=otzerling.com%2Ffeed%2Ffeedname
Is important because through the rss, events are sent automatically to the subscribed mailing list. The error is: connecting to feed failed.