Safari "loading please wait" issue

First of all: A huge thank you to the whole H5P team. You guys are amazing! I love your content and highly appreciate the simplicity of the whole H5P ecosystem.

I have one issue with one content type: Flashcards

The flashcards won't show up in safari, neither mobile nor desktop. It works perfectly fine using windows + firefox, chrome etc.

1. Open flashcards webpage in safari browser

2. Wordpress

3. Mobile and desktop

4. Safari

5. H5P 1.15.0

6. Flashcards (1.5.15)

7. Not available. Don't have a Mac

8. Nothing visible, already updated PHP

9. Loading screen "Loading, please wait"

10. No. Problem occurs in multiple websites with the same theme and plugins.

11. No, no recent changes

The content link:

http://3.0.58.3/farben3/

Thank you for any support!