Coinbase Pro API client_oid always empty

I've run into an issue using the Coinbase Pro sandbox API to test my software. When placing orders, I POST a client_oid field along with the rest of the body to the REST API, the order gets filled properly but when the received message arrives through the websocket stream, the client_oid is always an empty string.

Anyone knows why is that and how to fix this?

Example data POSTed when placing the order:

{
  "type": "market",
  "side": "buy",
  "product_id": "BTC-EUR",
  "funds": "1000",
  "client_oid": "dev_node-order-1"
}

And here's the matching websocket message of type received:

{
  "type": "received",
  "side": "buy",
  "product_id": "BTC-EUR",
  "time": "2021-08-15T16:57:29.079657Z",
  "sequence": 52030416,
  "profile_id": "[MY-PROFILE-ID]",
  "user_id": "[USER-ID]",
  "order_id": "d1f60730-8960-495e-a7eb-cd37baa46768",
  "order_type": "market",
  "funds": "995.0245866076",
  "client_oid": ""
}

As you can see the received client_oid is empty, any idea why?

Solution

So the problem was that the client_oid needs to be of the UUID format, for example 9bffcb70-13ea-11ec-abc7-7dfab310af81, if not of this format the field is ignored.