Are you able to reliably reproduce that spinning? I've been trying to reproduce it forever but haven't been able to reliably reproduce it in order to track it down. If you can send me that repro scene so I can take a closer look at it that would be great.
Thanks for the repro scene. If you click on the main character GameObject you'll see that the rotation doesn't change so it's related to the child ragdoll colliders. As a test I decreased the size of all of them and the character no longer spinned. The values that I used were too small though so it'll take some tweaking in order to get a good ragdoll. I guess I need to go back and do the same with Nolan.