I've found that using families + the LOS object seems to really glitch things up.
In my game I made a LOS system from scratch (since it's one-player, I was able to have a sprite for each zombie that was invisble and the width of the zombie. The sprite then stretched all the way to the player and if the zombie was less than X pixels away from the player and its LOS sprite didn't overlap a solid object, it could see the player. I also did some math to make sure that the zombie was facing the general angle of the player)