I have notice of late everytime I change realms my quest helper turns itself off.. Another thing when I leave my student at her home when I log back on she in the last place I ported from to my house..
When you use the "Home" function and then log off, you're teleported back to the commons last place you were before you used the "Home" button. If you were in an instance (i.e. a dungeon), you'll be put back in the Commons of that world.
If you walk into your home (i.e. through the door of the Dorms in Ravenwood), you'll be placed outside of the door, facing it.
That quest helper turning off , has been happening to me ever since a started playing about 10 weeks ago. I am not positive what is turning it off , but you are probobly right about it being porting or realm changing, Seems it happed to me more often to me on nights I am working through quest with friends.
The last place I logged out being buggy I can agree with , for about 2 weeks now , when I log on , it takes me to the previous spot , not the last spot I logged out . I am not referring to the house , but all over the game. When I log in the game now, I never know where I am going to land.