I just picked up the Chaos pistol, but I can't shoot with it while aiming. I can fire from the hip just fine, but that's it. I've tried swapping it with other weapons and they work fine. I've reloaded the game and tried removing the scope mod. Nothing I've done has resolved the issue. Has anyone else experienced this or have any suggestions?

EDIT: I tried upgrading the weapon. Now it's working again...