I can't imagine what would be causing LOS issues in CT (other players shouldn't), but it's possible this is a case of the camera LOS untargetable thing. You can't target something whose hit box is obstructed (from the camera's POV, not your character's) by another object. For example, when Garuda jumps and lands, I can't target her until I move my camera around from behind the pillar I'm hiding behind so that my camera can "see" Garuda's hit box. This is why so many people have trouble with the level 20 LNC quest; the hit box on the pile of bones is tiny, and the graphic of the bones themselves actually obstructs it from some angles.

The camera is generally the deciding factor with targeting things. Whatever targeting method you're using (tab key, D-pad, etc.), where the camera is pointed & what's in its field of view are just as influential (if not more) as what your character is facing.