Stand next to a fence and try to cast one of: magic missile ball lightning bombs next to it (look at it's splints) maybe others...
those spells will go through the fence. I'm guessing for some reason it's not checking if the spot is free to cast the spell there and give you the "no free spot" message.
There is a setting to allow/disable this - maybe these fences are set to allow it? Does it happen everywhere? I guess you are speaking of the new metalforge server?
Unless this is some magical fence, it will have holes in it (unless its a wall), so I don't see why stuff would not be able to go through the fence.. makes logical sense to me
I have tried this - I think it was 'destruction', if there's any such spell. It went through walls and everything and killed monsters in a room I hadn't even opened yet; that was in the cellar under Yarid's House.