I think the anchor performance as far as being able to tie dress and set, along with many other knots is dependent on the rope characteristics. I use the anchor every climb on poison ivy line. never any issues with loosening. Can you recall what rope was being used? are you positive your coworker tied dressed and set it properly?I used the anchor for years. I quite using it after seeing it loosen up while climbing. (The knot unties easily.) One of my co-workers in another office fell 30' because of this. I switched to the buntline, it is secure and I can untie it without unclipping the boner.