It is possible to set a group picture in a device groups.

The intention is to display this image as a header graphic in the Jamf Student/Teacher app in article style. But unfortunately only a placeholder (white space) is created in the app. The image will not load. 

If I remove the image from the group, the white space within the app is removed again.

Is it the wrong image format (PNG-8, PNG-24, JPEG)? the wrong image size? Or does this generally not work?

Another hint, "Ermitteln" is a very unfavorable translation in german. Perhaps "Discover: Entdecken" would be more appropriate.