The targeting in FFXIV, strangely, is based off of your camera and not your character. While mining, for example, you can be standing directly in front of a targeted node, but if your camera is facing away from the node you still won't be able to mine it because it is "out of sight" of the camera. I imagine in your case that little spike is a polygon or two from a wall that is right on top of your camera? In which case that wall is blocking everything on screen, rendering it all "out of sight".

The targeting in FFXIV has a few oddities beyond this too, I hope somewhere down the line the system gets an overhaul.