Grab on a survior from gen but they let go last sec

So i dont know if a bug or normal but i think is so confusing when you get the grab animation on a surviors that is working on a gen but they let go from the gen last sec, that counter the grab animation is little bullshit. i mean if you get the animation of a grab on a survior on a gen , then you shoud get it. so many time i get the animation of a grab, but it stop for 0.5 s since the survior let go of the gen and i am stuck 0,5 s - 1 sec and they run awaye with out geting hit or grab. It is just my opinion i understan many think is mabye fair game or not , but i just woundering about it