From what I know, the reason why you have a blank rank ingame is that your current rank is next below a banned player.
For example, "Player X" is currently Rank 2000 with an estimated EXP of 560,000,000 who is banned for using hacks while you have an estimated EXP of 550,000,000. Then your rank will be represented as blank (-). Unless that banned player will eventually get unbanned, then your current rank will be 2001.
