Internal server error when creating groups hold

Question

I'm getting the following error when performing a matters.holds.create call.

The body is:

{
  "corpus": "GROUPS",
  "accounts": [
    {
      "accountId": "account_id"
    }
  ],
  "name": "my name"
}

The error:

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

What could be the cause of this?