Since Summerset, enemies are able to shoot with fireballs etc, through walls and hills.
Good example pre Summerset:
Using pickpocket on a Mage-NPC inside a building but you fail. You don't want to kill him, you're running behind a wall and he has to stop casting to get you in sight again.
That way you can easly bypass the "being infight" time to escape through a door.
This could be applied on any wall/stones/hills or anything what would be inbetween you and a enemy. It's logic and i always loved that this behavior was used in ESO. It made it a especially good game.
Since Summerset:
You use pickpocket inside a building on a Mage-NPC but you fail. He will shoot at you no matter what, you can't get out of sight, not even a bend wall will stop him looking and shooting at you, he just shoots straight through.. This applies on anything what could be inbetween you and a enemy. A archer just shoots strait into your feet through a hill, he dosn't care.
This is complete unlogical and rly stupid.
I don't even know, if developers inteded this behavior, or if it's a mistake.
Will this be changed back/fixed any time soon? It's one of the reasons i stopped playing ESO.