This may well have some logic to it that I'm missing.. But I frequently end up in situations where all I get while targetting opponents is "This target is invisible". No invisibility cast, nothing hiding them, and well within range of a spell.
So, on not being able to cast/strike them, turn is called, and they're perfectly able to hit me with range (with no movement).
Also I've noticed things on the ground (such as skeletal piles and so on) seem to block vision. That really shouldn't be the case, as they're on the ground, well below line of sight/weapon pathing.
Is there something simple I'm missing in this?