I have had this problem for awhile. I will see a server with lets say 12/20, I will join said server and there will be no one in it..... I CANNOT find a server with anyone in it. Its always empty and says it has people. Any ideas?
Try refreshing your server list. At default, I believe that if you close the game, then re-open it, it will use the server list from your last refresh. So I would advise refreshing your server list and see if that gets rid of your "ghost players".
AFAIR (This was like 5 months ago, since I finished single player and couldnt play MP I uninstalled) I did not minimize and I did click refresh server list.