Multiple Categories no longer working

I’d like to assign events to multiple categories.
When Type of Event Form Field “Categories” is set to “Mehrfachauswahl Begriffe” (Term Multiple) categories are no longer displayed on the single event page and therefore it is not possible to select any categories.
When Type of Event Form Field “Categories” is set to “Begriff ausw?hlen” (Term) the categoires show up and the event can be assigned to a single category but not multiple categories.

Tested on WP 5.9.3/6.0, WP Event Manager 3.1.27