Preview of real time template not showing up when checking with seed address
Hello everyone,
I face an issue with one of my real time template
I input the HTML and when done, I want to check with a seed address the preview to see how it looks like but when previewing, there isn't any display : see screenshot below.

Why is it doing that ? I also try with a simple test HTML, the preview won't show either. (main error is there, not happening with my other templates)
Any idea on how to fix that ? I think there is a reason why when I want to test this real time that I got an error that mention : event not covered.
I make sure that the event type is linked to the template and the template is successfully publish.

Thanks for your solutions.
Kind regards.