An idea Iv'e had for a little while now, either cliche as all hell, or somewhat good (I can only hope).
Right off the bat, the concept of a mysterious undetectable being is covered in a few other articles (along with the exploration of paranoia). Said examples range from 303 to 2740. As such, I will suggest to rethink the anomaly in how it works.
All methods of locating or identifying SCP-XXXX have met with failure, the only conformation that SCP-XXXX remains in its original location is its continued effect on subjects.
The former clause is kinda contradictory, since the Foundation ultimately deduced its supposed location and even claimed it to be sapient. Did the Foundation confirm that it is sapient? What is the SCP as a sapient being?