When you join the server as an OP, you have automatic the Silent join and silent left. In the config file I have this: allow-silent-join-quit: false
And still operators gets no joining and leaving message and all other players do have the message.

make sure they don't have the permission node to do that and also I think this was changed in the newest version which you can find on their jenkins, try doing that then maybe ask for help in their support discord server