A lot stables windows are bugged, if you see through them, you can see just terrain, no objects and stuff. And of course you can see players. This happened to me in Stary Sobor, beisdes tents.
You just need to go in front of a window, inside the stable, and standing near or a bit far from it. Almost all of them are glitched.
Playing on the 0.60, updated on the 9th of June.
