Custom tile shows default icon

Hi all,

I created a custome tile as an admin from the Admin portal and all users are able to see the tile from the My apps view. The problem I have often the image I set in the tile settings (an image from SharePoint Online, shared with Everyone) isn`t shown to the users, sometimes it does show up. Most of the time a default icon is shown (image with 2 blocks). Does anybody have the same issue and knows a solution to this?

Thanks!

Peter