Originally Posted by xMotionSickness
I tested this earlier for you. My playtime on global leaderboard said 1 day 17 hour 14 minute, I went to track central and played Norfair's track on RedLynx Picks, I must have spent a good 10 minutes on it but my playtime remained the same when I went back to check.
Maybe it takes a while to update?

There is absolutely no way that counter is only counting official single-player tracks.