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Hi ! Thanks for your answer.

I switch to Twenty Twenty theme, then to Twenty Nineteen, and still have the issue on both of them. And I wrote exactly the same shortcode as you did in the video.

But, I found where the problem was. I use the Classic Editor plugin to remove Gutenberg, and there was the problem. When I switch off this plugin, it works !

I don't know if you can fix it for a next update, but meanwhile, I won't use Classic Editor plugin anymore, even if I prefer this way of build a WordPress Page.

Thanks for your help 🙂