Ok so I think I was able to track this down and clarify the bug. If you have a character and you have ever used the paid character transfer service (the one for 1999 NC coin) to transfer that character to another server, that character will then be bugged. It will not be able to do the level 60 quest line. The quest and all related quests will be marked as completed, just as if you had used a level 60 voucher. If you are not already level 60, the character will be bugged and unable to progress.