Master of Deception

Hewllo rogues! I'm leveling up my next rogue and I'm level 38 now. I've been playing for a long time and my eye is trained for detection distance. But this time it seems like something is wrong with it. At first I thought it was the combat spec, but when I spec'd into a sub, even with 3/3 Master of Deception I was still being detected by enemies extremely far. So much so that the whole point of using this talent is lost. Have you noticed this problem? Maybe it's a bug? It looks like a bug, but maybe I just don't understand something. By the way, my rogue is a human with racial perception and the last time I fought an NPC rogue, he stabbed himself with a backstab ability. Could the same thing happen with a racial ability? :D