This issue has been closed as 'Won't Fix' due to an extended period of time without updates. If this issue is important to you please let us know by posting on the AnswerHub or UDN, and Epic will re-open the ticket for further review.
Seems that by manipulating blackboard key selector in BTNode_RunEQSQuery one can lose values set, and make BB key selection lose it's filtering (runt eqs should accept only locations and actor here [or derived types]).
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-13961 in the post.