Google Cross-Account Protection (RISC) API. Callback endpoint registration returns 500 Internal Server Error

Question

I am trying to register an api callback endpoint in google Cross-Account Protection, but I keep getting a 500 Internal Server Error response with the following body:

{
  "error": {
    "code": 500,
    "message": "Internal error encountered.",
    "status": "INTERNAL"
  }
}

HTTP POST Request:

• URL: https://risc.googleapis.com/v1beta/stream:update
  
• Body:
  

{
  "delivery": {
                "delivery_method": "https://schemas.openid.net/secevent/risc/delivery-method/push", 
                "url": MY_CALLBACK_URL
               }, 
  "events_requested": ["https://schemas.openid.net/secevent/risc/event-type/sessions-revoked"]
}

The authorization token is generated using the script from the official documentation

I use the following curl request for testing:

curl -X POST https://risc.googleapis.com/v1beta/stream:update -H 'Authorization: Bearer `AUTH_TOKEN`' -H 'Content-Type: application/json' -d '{"delivery": {"delivery_method": "https://schemas.openid.net/secevent/risc/delivery-method/push", "url": `YOUR_CALLBACK`}, "events_requested":["https://schemas.openid.net/secevent/risc/event-type/sessions-revoked"]}'