After meeting the miller I noticed it was twice in the list of people: once with the icon and once without. I do not know what triggered this though.
That's interesting. I've seen "Phantom" things appear at the very bottom of lists when using the list component in other apps. Not yet in the games though. Perhaps it is that. I'll check it out.
I just tried a new game and managed to duplicate the problem at will (on the Mac version). From the start do this: jump w, w, s, look at miller → miller without icon appears. It seems that the correct miller object appears only when looking at him inside the mill, but while still in the field, where he's visible through the window, the iconless object appears.