[Rogue] Vanish doesn't fully drop Aggro

As I want to make sure that I am not imagining things, I'm posting these here before I make a bug report. Here's my problem with Vanish.

What I would expect: after I use Vanish in a boss fight, if other party members in the group are alive, the boss will aggro them. Once they are all dead, the boss will reset.

What actually happens: after I use Vanish in a boss fight, if other party members in the group are alive, the boss will aggro them. Once they are all dead, the boss, regardless of my whereabouts, will proceed to aggro me again and attempt (usually successfully) to kill me.
Interesting to note that, if no other party members are alive when I Vanish, then the boss will indeed reset as I Vanish.

I had never experienced this in the official servers as far as I remember, so I'm pretty sure it is not intended behaviour. Furthermore, the problem only appears to be happening specifically to Vanish, and not to other threat zeroing abilities such as Feign Death from Hunters.

Can you guys confirm this is not intended behaviour?

That's how it worked on TBC retail. Raid boss puts everybody in combat which continually pulses. If you have your scrolling combat text enabled with Combat entry/fade enabled you will see your combat state drop and reinstate itself after your vanish. Best way to survive a wipe as rogue is to completely stop attacking and spam feint until you are the last living raid member at which point your vanish will work because both you and the boss will exit combat together which will turn off his pulsing combat state.