I encountered a variant just now that I've not seen before. Latest patch & hotfixes. Act 2, Moonrise towers. Gale is in Ketheric's throne room downstairs. The big double doors to the entrance hall are wide open and 2 absolute warriors are on the other side. Gale wants to cast an AOE spell on them, but it won't "fix" on them. Neither Fireball nor icestorm. He then tries a magic missile on one of the two. The victim "lights up" (red contour), the circle is shown that counts down the magic missiles, but clicking the mouse does not trigger them. The victim is in sight, there is no message whatsoever saying why the missile can't be fired.
I turn to another enemy on my side of the door and this works normally.
Fights are tough enough without this kind of sabotage. Especially when you spend some time deplying you characters over the place for tactical advantage.
