Well, since you are keen to "answers" it's a problem with memory address in fact, the game is operated by three world services, separated, and so there is something called memory address that is a pointer, helps those programs gets your character's data. We've made lots of modifications to the service that operates the channels, they control the mem_addr and when gameservers asks for it, they provide it. Expect, when groupserver fails and restarts it may have wrong mem_addr, and assigns to an gameserver but expect the gameserver has no such memory address.
So why is this becoming a problem all of sudden? Well, we're changing a lot of things that includes the tools/compiler and the brand new code that supplemental some of newer game features, combined it's causing unexpected behavior that makes those application misbehave.
Correct direction is to debug and catch the application misbehaving and place corrections, instead of rolling back files/configuration as it is just two steps backwards.