I can definitely understand the importance of being able to create your emails as easily as possible. This error message you're receiving is something we are currently collecting information on for further troubleshooting. For instance, is this a campaign you copy and reuse often? Also, what browser are you working in? If you have not yet tested your browser, I would suggest trying a different browser or a private/incognito window. While we do not have a time estimate for when this will resolved, one workaround we suggest is recreating your email in a new campaign. I apologize for any inconvenience this workaround may cause. In the meantime, we have also added you to our queue to be notified when this is fixed.