This is still an issue, I did the same thing and Cecil is stuck at the top of the stairs making the open door animation and is not able to be interacted with. It seems not following him up the stairs quick enough causes him to glitch out.
I should mention I didn't follow him in sneak mode, I went into sneak mode and stole everything on the first floor, then went up and he was unresponsive.
Last edited by Lateraliss; 23/01/14 03:45 AM.