Joe McCarthy wrote on Jan 3^rd, 2017 at 12:54am:

It means they found something in your personal history they didn't like, in my opinion.  Either someone has said something about you when they called references and family.  If this is the case, you have bigger problems than not getting on with METRO; you have a rat.... A gnawing heaving rat in your circle. Having said that, base on my experience, it is usually something on social media that screwed you over.  one or both, are distinct possibilities. Just my take based on the limited information.  P.S.  I hope I didn't say anything you'd find offense.  I have a unique sense of humor

This is exactly the problem I had with my IC applications.  Based on my FOIA/PA requests, I believe that my rejection was due entirely to the BI.  Unfortunately, the BI'ors were able to "develop" a series of informants (all at one employer in particular), not authorized by me, who went out of their way to provide incorrect/inaccurate accounts to the investigators.