It happens sometimes, that when you are aiming with a bow, at the moment when you want to shoot, the character gets "tired" and stops aiming. If you click left at that very moment, the arrow goes back in the quiver, forcing you to pull it out again.
I suggest a small change:
Arrow goes back in the quiver with left mouse button ONLY (not holding right mouse button)
It should not happen when you are holding right and click left (because that means you want to shoot).
Customer support service by UserEcho