RSS feed for events doesn't allow sorting

So we have an rss feed of events, scheduled in Mailchimp to go out as a mailer to our database whenever there is new content.

We published an event for 7 Feb and it went out to no problem, the event hasn't passed yet as it only begins today at 6PM and we need to publish another new one for next week, but it only allows the first event to populate the feed within the mailer.

Anyone know how to get around this issue?