category default layout - empty registrants pop up

Hello!

Unluckily I do need help with showing an event's registrants. I'm using the "category default layout" and everythime someone wants to see the registrants a pop-up comes up - but nothing happens. Only an empty white pop up appears.

I enclosed two screenshots. The word "Teilnehmer" means registrants in German. What do I have to chance to display the registrants. And is the only way to show them using a pop up?

Thanks a lot in advance....

Cheers,
Frank

Maybe there are something wrong with the settings or css conflict. Please submit a support ticket sending us super admin account of your site and the link to the page which we see the error

We will then check to see why the issue happens and get it sorted

Regards,

Tuan