This "Failed to find bit state" error is quite unhelpful. I'm hitting the same thing five years later. And, to my surprise, I can manually change characters of a DeviceCheck token that I pass up to Apple's servers and still get "Failed to find bit state" instead of something like a Forbidden 403. I was hoping that any invalid token would produce a 4** and any valid token would produce a 200 with the status of the bit state consistently returned as JSON. This API contract is poorly designed

Thank you! I just came back to this project. I'm happy to see @Natan's find below too!

Great tip!

The first error I see in the logs is "unexpected error getting preference domain for service com.apple.cmio.registerassistantservice.system-extensions: Connection invalid". Searching that string does not turn up anything on google. I'm on Sonoma 14.0 Beta (23A5286i).