May be just an issue in Connecticut where this happened, but of course the ATF is a Federal outfit so.....
http://www.thefirearmblog.com/blog/2018/05/24/oal-brace-folded/
According to Victor Benson, proprietor of The Freedom Shoppe, the ATF is measuring his firearms with the brace folded and declaring his firearms as illegal AOWs.
http://www.thefirearmblog.com/blog/2018/05/24/oal-brace-folded/