Good evening Marion and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about the short codes not displaying properly on your site.
I would love to help you with this topic.
Thanks to your explanations, I was able to locate the cause of the issue.
What is going on is that your shortcode is wrapped in
and
tags (see screenshot).
Removing these tags should fix things (using the “Text” tab).

Let me know if that helps.
Have a great day!
Geoff B.