Riding back from finishing cartographer this morning, I took a short cut east of the black keep, through the icy crevasses. I was riding around the King Rocknose when I got chain disconnected. I had two thralls with me, who killed the King, and after he was killed the chain disconnects stopped and I was then finally able to log back in, collect up my thralls, and go on my way.
Please look into the King in this area (or a memory hole in this area) as it seems to be bugged with a chain disconnect whether you’re engaging King or just riding through.