Went into game, screen shake stops the vibration after casting eldritch blast, but the warm up animation you mention can not be turned off. What is happening is a light bloom/visual distortion bubble that bends your view like a fisheye lens on both the caster and the area where the blast hits. Turning down graphics and post processing did not remove that light bending animation.
I am still unsure what targets are gyrating around so much in a stationary position that it is causing targeting issues. Idle animations do move character models around a little bit but the "hit box" should be consistent. Even as they sway back and forth if my cursor is in the air "next" to their head, it is still targeting that npc. Melee targeting has been a little buggy, as I'm point blank but sometimes it wants to run off a little bit to get a melee attack in (causing an attack of opportunity), that is an issue with pathing, but I have not had your issue where I can't make a hit because I am too far, even though I am next to the target.
