It is. When you go to leaderboards, you have to scroll down to a different game mode. There's like Green Run, and all those other maps. There's gonna be four leaderboards for each different map, representing how many players there are (the dashes on the bottom right of the picture shows the number of players for that leaderboards).
I'm not sure if custom games counts on the leaderboards, but it should in my opinion. I played on Easy difficulty and it didn't show, that could also be a reason.