@psychobunny I believe it has something to do with CentOS or running Plesk/cPanel as I have not for the life of me been able to make it work properly, even with that guide. We are switching to a Debian server soon without Plesk or cPanel so hopefully that will render the issue solved.
I just tested to create a new group and following two issues occured
bug: using svg-images for header works fine until "save" gets pressed. save responds with "error".
feature-request: I'd like to set the background-size to contain and center the position.