Legitimately cannot find it, even zoomed in. Are they meant to appear after only three room transitions? It made getting the Fire Bloodstone far more difficult than it would have been otherwise. On the topic of Ghouls, consider renaming them Wraiths due to their ability to walk through walls as well as putting them on the front layer so they aren't obscured by the terrain.
Viewing post in Bug reports
It's not perfectly visible, but you can see the red glow moving while in game. But I can adjust it and make it more visible no problem. My goal is to just give a hint that something is there, not to make them light up like a lightbulb.
This is how it looks when I increase the brightness
Their ability to walk through walls is just a placeholder until I get some form of pathfinding working. Without that, they would be completely useless and not dangerous at all. Once that happens, they will walk around obstacles like you would expect them to.