Roughly after Sister of the Thorn being added, I have noticed a change in how specials act. For example, although assassins will sometimes take a few moments to get to you, generally after you hear the sound, you know a pounce is coming soon. This is no longer the case. For example, on Fort Brachsenbrucke, I heard an assassin spawn, he then proceeded to run towards us, turn around, run out of the fort climb some walls and mysteriously disappear. Only after we completed the event and we were entering the Bridge of Shadows did the assassin finally pounce.
This is not isolated to assassins, nor the map Fort Bracksenbrucke. I watched fire rats run away instead of spew fire at me, and now I occasionally see hook rats stand still for seemingly no reason. Strange behavior like this in my long time playing this game was generally rare, but now I see it almost every mission. Perhaps members of the community have video evidencing this point? I am not one to record my games.