How often do the Gamemasters get online?

[Lexical]

sounds like a database update error or a db relation isn't properly linked. If they patched certain values in a zone table or however they have it organized, it could cause a link between two tables to become severed which would be why you would need to get the single point of XP to cause the update which returns all the xp your character has. Don't quote me since this is all speculation as I don't have access to their code. :P