It isn't. It really, REALLY isn't. And it is breaking the game completely for me. First time I loaded my ranger character the companion is gone. Since I am now reading that it doesn't only happen for companions but also followers, why would I want to make a new game if it will just happen all over again?
Until there is a proper fix for this, PoE will have to sit in the dark corner of my Steam Library and remain unplayed.