So I've found the problem.
on an online server of "mongodb-server" was installed.
when I changed it into "mongodb-org-server" He has shown the groups.
So it could be because it is located on the MongoDB.
If there were multiple topics with the same slug I would show the user a list of those topics with a summary text of the body content and allow them to click on the one they want to read.
Anyone know of some sample code to find a list of topics based on the slug?