Targets all within 50 paces or yards, NPC and quest itrms that to the game mechanics are there and you can collect as well as mobs that can see you, attack you you can use say Bone Chill cold spell it but everything else, CANT SEE TARGET.
I realise terrain construction is a use large objects and hide some of it process and that there are invisible walls all over the game that stop you dead in your tracks but NPC can walk through. This isnt the first time Ive reported this and I doubt it will be the last.