Forgot to mention it in the original post.
Not quite like Vauban's one cause, even if you kill the enemies inside the bubble, they just don't get pulled anymore.
I noticed it in a mission for the first time, and then tried as many combos as I could think of in the Simulacrum.
Sadly, can't find a way to make it consistent and make other people easily replicate it.
I thought it was a number problem, so I spawned 15-20 enemies but, sometimes, as soon as the enemies die inside, they get pulled and sometimes they don't.
I tried to spawn 1 or 2 enemies and sometimes they always get pulled,