sorry , i dont understand, what is ironic about this? , this happens sometimes whats the problem? why cant this simple problem happen with 10mm

Look at the reduced space between the nut and the hanger. The powers that be here in France have been obliging equippers to use 12mm bolts instead of 10mm in the interest of safety for quite some years now and have unwittingly created something quite the opposite. This can't happen with a 10mm bolt. Sure, the krab can turn into this position with 10mm bolts, but it can't jam in that position. This krab had to be forcibly levered to free it. I'm quite convinced that if I'd taken a fall onto it, either the quickdraw sling would have ripped the gate out or the krab would have snapped.

Surely a slightly larger hanger would solve the jamming problem by increasing the gap between the eye of the hanger and the hole for the bolt?
Perhaps a company like Petzl could manufacture some new more appropriate hangers.

why is the hanger horizontal anyway? If it had been placed with the hole in the vertical plane then it's unlilley there would have been a cause for jamming and any force would have ben distributed more evenly to the bolt and the krab. Simple mechanics which perhaps isn't appreciated by many who place bolts

The hanger isn't horizontal. It's perfectly placed so that the point where the krab sits when initially clipped is vertically below the centre line of the bolt. The krab isn't hanging downwards, it has turned and jammed in that position - the spine of the krab is horizontal - and was very difficult to release, which was the point in posting the photo.

To make it a bit clearer, the rope is vertical.