Thanks - this has now been fixed, so your stats will start being tracked at the next system update.
Interestingly, what appears to have occurred is that your account did not appear on the RuneScape highscores at the time of the initial stat capture. When an account does not appear on the RuneScape Highscores at the time of the system update, the system assumes that the display name is no longer in use and temporarily turns tracking off for it.
This happens pretty often during display name changes - however, a display name is actually checked for potential re-activation every time someone visits a profile page, so generally via this method an account is placed back into the active state when it re-appears on the RuneScape Highscores (maybe the player was unbanned, changed their name back, etc.). In your case this didn't exactly work, because you never had a profile to begin with, so your account was never re-activated. However, this should now be fixed.