I just had the problem with our setup in which users existed and could be pulled from our ldap server but they didn’t show up in their groups which also showed up just fine.
The problem was the user:group matching which can be set in advanced ldap settings under user group association. You will have to try the different association methods until your groups are filled with users. This took me a couple of hours to find out. I’m writing this here because there is not a single place on the internet where this is mentioned