Just gone to take my cranks off. Removed the 8mm bolt but the cranks stayed put. Looks like Canyon didn’t install the ring for the bolt to push against. Presumably that is a fault I should get back to Canyon about? It’s not an optional extra?

You should have the bolt and the ring, as here:

https://www.ebay.co.uk/itm/Sram-Crank-Arm-Bolt-Kit-M18-M30-Self-Extracting-DUB-Black-1pc-/274137572749

The outer bolt is not optional.
£15 gets you riding again as soon as possible.
Try canyon, but I bet they take ages to get back to you. Annoying really.

The bottom bracket was creaking but not loose. Thought i’d have an explore with a new bb in standby. When i realised i was beaten i spayed it with wd40 and put hhe bolt back in and redid the preload. It didnt squeak on the up and down the road test so im fine for now. Thanks

Our trails are littered with the SRAM extraction rings. I could probably pick up 1 per ride if I looked hard enough.
Yours probably fell of on your first ride.

Our trails are littered with the SRAM extraction rings

Have you got a dodgy bike mechanic locally who tortures people by removing these rings?

I’ve had countless, and worked on countless SRAM self-extracting cranks and never had one come lose on it’s own!

It seems it’s this year only. A new craze.
Of the 3 I’ve picked up this summer, none of them had loctite.