Although it was locked on based on the aura of the Law, once Shen Hao arrived in the vicinity, the Small Map showed their positions with crystal clarity.
The worlds where these three Demon Lords resided were near each other, which for beings of their level, made no difference from being gathered together.
In addition, Shen Hao realized that all three Demon Lords were indeed doing their utmost to conceal themselves.
One of them, in particular, had shrunk into a ball, sealing itself completely with layers of weirdness.
Not the slightest whiff of its aura was leaked.
Under such circumstances, unless Shen Hao came nearby and sensed something, or the Small Map explored the area, it would not be surprising for one to not discover the Demon Lord hidden within, even if the entire region was swept clean by a Human Civilization Legion.
If all the Demon Lords were like this, it would not be strange to be unable to find them.