Errors in follow up Attendee emails in webinars

Recently we noticed that the follow up email for webinars attendees does not reflect the updates made. 

We conduct many webinars and update the follow up email for attendees. Recently we found that even though the preview email sent to myself is updated, the email that attendees receive does not reflect the changes and is outdated. This is a major concern for us and generates misinformation among our attendees because, for example, we tell them in the webinar that they will receive certain information, change the follow up email to include it, verify the changes with a preview email sent to myself BUT then attendees do not receive the information. 

Please, what can be done to correct this terrible malfunction?