Hold open don't work right.

I got this strange problem that is my weapon's Hold open animation works very strange.
It do hold open while I shoot my last bullet any of my gun.
But once I press reload. And my weapon like pistol or other guns with hold open features.
The slide on it will just slide back to normal position before my character have reload a new mag.
And after my character done loading a new mag. the animation became load the gun without hold open.
(like Glock. If the slide is at hold open position. The loading animation is after loading the new mag. Your character will press the slide stop to chambering.
But mine is I just press R and then the slide just go back by it's own so my loading animation will be like pull the slide to chambering.)

My game still works normal. But very annoying and distraction with this not smooth loading animation.