I'm not sure why, in open areas or more closed areas, like a sewer for instance, I've had activators cast sometimes and not others. For instance I have some scripted percentage (proc) based enchants and the activator wouldn't always cast when it was supposed to, which is that sometimes it would and other times it wouldn't and for no particular reason either way. Script was fine as an aside, I ended up just going with player.casting and sucking it up that the player casts the proc buff on themselves but it breaks immersion in my opinion.