Hello my problem is that i can’t add myself to groups i have created. (It’s an admin admin account)
One example of a consequence not being in a group is that i can’t see the group folders i’m not assigned to.
I can add myself via occ comand but it would be nice to have that feature on the graphical interface.
Here is a screenshot of the problem. The is edit icon is missing on my user account.
same here since Nexcloud 18
Download the app:
occ web
And you will be able to put youre self in a group by:
group:adduser <group> <user>i already wrote that i was able to assign the group via occ comand in my first message. So it’s a bit of a redundant message 
Okay there is a better way to solve the problem with not seeing the groups.
It’s not even necessary to for this particular problem to have the admin in any other group.
Just leave the admin-user in his one admin group. And add the admin group to all the groupfolders in the groupfolders setting.
Sorry that people want to help you, but doesnt saw that line in youre text.
yeah shame on you 
but thanks anyway 