I've had a hollowtech 2 failure on my commuter bike (Alfine 8) that I couldn't seem to find anyone else has had (and therefore no way to fix)

The drive side arm has become detached from the spindle. I've tried to show in this gif what's happened:



I also got some metal bits out of the centre of the spindle which I expect were important:



The tension cap was done up hand tight and I used a torque wrench on the pinch bolts. Bike hasn't taken any abuse from my knowledge, but has been parked at the side of the road from time to time.

It seemed to just progressively get worse, there wasn't one incident that seemed to cause it.

Anyway, just thought I'd document this in case someone searches for other failures.