Hey @Guido4 .
Thanks for reaching out.
I appreciate that you have provided the URL to your online store. Just to gather some additional context, when you navigate to your online store using the Preview option when viewing your product? I took a screenshot from my test store to show you the option I am referring to:
I would suggest attempting to clear the cache on your browser and try this action once again. In some cases, clearing the cache from your browser can fix minor issues that you may experience on the Shopify platform. If the issue persists, try to use a separate browser. For example, if you are using Safari - try this action on Google Chrome.
Let me know if that does the trick, looking forward to your response.