In this case, I found several ways to solve the problem of the already stopped animation. (NOT WITH ITS CAUSE), you can remove the gun from your hands simply by pressing the hotkey so that it disappears from your hands and when your hands are empty, you have to attack, then the character will hit and go to the usual idle position.

You can also get an axe and then put it behind your back so that the character can take a pistol from idle position

When the animation stops, the engine thinks it has played it and thinking that the gun is in your hands, so that you can take aim from the 3rd person, but when you switch to the aiming mode from the first to the rear sight , the camera moves behind your neck and will look in the direction of the muzzle of the gun.