Venomous Glider
Whenever the danger sense failed to warn its user even when there was clear evidence of a hostile entity in the vicinity, it was due to one of three reasons.
One, the entity was too weak. If the danger sense deemed the hostile aura being emitted too feeble and therefore, incapable of posing any significant threat to its host, it remained silent.
Secondly, the danger sense could only alert its host when it was more than 50 percent certain that they were the one in immediate danger.
Last but not least, the danger sense was aura-dependent. Creatures that possessed no aura whatsoever or used skills or artifacts of some kind to mask their aura were practically invisible in front of the warning mechanism.
This was why artifacts that specialized in concealing aura were treacherously expensive anywhere you went.