This bug started on live some time back. But it started only when after you used a buff like Build-Up or Aim or some other toggle/click that utilizes the same animation. Now, it doesn't seem to matter, it just happens whenever. Been trying to get Devs to look at this since when I first noticed it on Live. Since it's getting worse and affecting a lot of players now, I'm hoping it finally gets a fix. It happens on my Illusions/Time Troller too, along with my Ninjitsu Stalker, and almost every blaster. Why the combat stance bug is getting worse is anyone's guess.