Canon 1.4x extender III with 5D Mark III and 100-400mm II issue

I carry the above connected on a Rapid Sport camera strap. For unknown reasons since I have had the extender it has uncounted from my camera 2 times. Since my strap is connected to the tripod collar on the 100-400 the camera has fallen to the ground, luckily it appears camera is okay. I have recently attached a harness from tripod collar to camera and this has prevented disaster two more times as the harness prevented my camera hitting the ground. Once the main lens uncounted from the extender. Any ideas? I have only had the extender a few months.

And the extender is an actual Canon part, right? (It's in the title of the post, so I assume yes.)

Assuming yes, that seems really, really surprising. I have one of each (1.4 and 2x) Canon extenders and they feel rock solid. And I really shouldn't but I've even briefly held the 5D3 by the (normal) hand grip with a 1.4x and 600mm prime (at 12 lbs) hanging off the body as it feels that secure.

Is the locking pin on the extender engaging properly? Can you loosen the extender from the body by twisting it and not pressing the release level on the extender?

They are all Canon parts. I bought the extender direct from Canon. Really unnerving to say the least. They lock in and no the dont come Indonesia got twist of pull. I will have to examine pins tomorrow. Thought maybe the camera strap buckle was causing it as the camera is at my waist level.

marklori43 wrote in post #19054593
They lock in and no the dont come Indonesia got twist of pull.

English isn't my native language, so maybe that's why I don't get what Indonesia has to do with this problem? Anyway, isn't the fact that you have attached the strap to the lens the original problem? I'm not sure if you by uncounted mean that the extender gets disconnected from the lens, or the camera from the extender? But I've seen that a strap holding a lens can press on the camera's lens release button, when the camera/lens combo is hanging from the strap.