Google assistant integration error with private openhab-cloud server

I have a perfect error-free config, where google assistant is working through myopenhab.

I would like to switch to a private openhab-cloud server.

I was able to install and configure a working local openhab-cloud instance. The openhab server connects and is visible as ‘online’. The instance is accessible and secured.

I have followed https://github.com/openhab/openhab-google-assistant/blob/master/README.md, and I was able to deploy the cloud instance.I have created all the necessary credentials, added mongo entries etc. I am able to see my “[test] appname” connector, and I am able to add it to Google Home, and the OAuth2 page appears for the scope “Access to openHAB Cloud specific API for Actions on Google Assistant”.

Problem:

After clicking ‘Allow’ on the oauth page, “signing in” and “linking your [test] app” appears, but then returns the error message “Couldn’t update the setting. Check your connection.”

The following events happen after the click:

openhab-cloud log prints “info: openHAB-cloud: server.authorization oauth2 request for scope: google-assistant”.

In mongo, db.oauth2tokens is getting populated.

console.cloud.google.com/logs shows errors upon the failed requests:

“Google Assistant Action” :

{
  "textPayload": "SYNC: Request ID 2390446658650635853 failed with code: OPEN_AUTH_FAILURE",
  "insertId": "1j7ypurfej0qs1",
  "resource": {
    "type": "assistant_action",
    "labels": {
      "version_id": "",
      "action_id": "SMART_HOME_SYNC",
      "project_id": "security-287110"
    }
  },
  "timestamp": "2020-10-24T15:06:07.759185401Z",
  "severity": "ERROR",
  "logName": "projects/security-287110/logs/actions.googleapis.com%2Factions",
  "receiveTimestamp": "2020-10-24T15:06:07.764469136Z"
}

“Assistant Action Project” :

{
  "insertId": "lnhtrdfu7vvvv",
  "jsonPayload": {
    "syncLog": {
      "syncs": [
        {
          "status": "OPEN_AUTH_FAILURE",
          "httpLatencyMsec": "128",
          "requestId": "2390446658650635853"
        }
      ]
    }
  },
  "resource": {
    "type": "assistant_action_project",
    "labels": {
      "project_id": "security-287110"
    }
  },
  "timestamp": "2020-10-24T15:06:07.763034077Z",
  "severity": "ERROR",
  "logName": "projects/security-287110/logs/assistant_smarthome%2Fassistant_smarthome_logs",
  "receiveTimestamp": "2020-10-24T15:06:07.763034077Z"
}

I have checked a dozen times at least, and client ID, client secret are all correct and matching in both mongo and the Actions console. I have tried two different OAuth2 credentials, and the errors are the same.

What I have also noticed is that the local instance of openhab-cloud does not populate the “Application” and the “Description” fields in the account/Applications menu point. myopenhab shows “Google” and “Google Assistant Voice Control” here.

The openhabGoogleAssistant cloud function does not seem to receive any invocations, at least according to the cloud console.