Google calendar add-on for conference solutions using alternative runtimes doesn't appear in dropdown

I followed all the steps, by creating google cloud project, enabled the Google Workspace Marketplace SDK and in Alternate Runtimes tab enabled the Add-ons API. I created a new deployment for the add-on and the configuration looks like below:

{

  "oauthScopes": [
"https://www.googleapis.com/auth/calendar.addons.execute", "https://www.googleapis.com/auth/calendar.events.readonly", "https://www.googleapis.com/auth/calendar.addons.current.event.write", "https://www.googleapis.com/auth/script.external_request", "https://www.googleapis.com/auth/script.scriptapp"],

  "addOns": {
    "common": {
      "name": "Waitroom develop addon",
      "logoUrl": "https://lh3.googleusercontent.com/-WuPhRsFGKUc/XCng7m_FIxI/AAAAAAAAAGg/ASH4GCGDMs0d55OZQGCSIQHXjRAKnkeTQCLcBGAs/s400/jitsi-logo-96x96.png"
    },
    "calendar": {
      "conferenceSolution": [{
        "onCreateFunction": "https://wormhole.develop.waitroom.com/v1.0/google/calendar/create-session",
        "id": "1",
        "name": "Waitroom test",
        "logoUrl": "https://lh3.googleusercontent.com/pw/AM-JKLUkiyTEgH-6DiQP85RGtd_BORvAuFnS9katNMgwYQBJUTiDh12qtQxMJFWYH2Dj30hNsNUrr-kzKMl7jX-Qd0FR7JmVSx-Fhruf8xTPPI-wdsMYez6WJE7tz7KmqsORKBEnBTiILtMJXuMvphqKdB9X\u003ds128-no"
      }],
      "eventUpdateTrigger": {
        "runFunction": "https://wormhole.develop.waitroom.com/v1.0/google/calendar/update-session"
      },
      "currentEventAccess": "READ_WRITE"
    }
  }
}

So the issue is after installing the add-on. The add-on appears in the calendar on the sidebar but the add-on doesn't appear in dropdown. Refer the screenshots and the video for more details.

Add-on appear on sidebar Add-on doesn't appear in dropdown

I tried reaching out to google support however failed to get the issue resolved. I made sure the suggestions from the support were followed, refer to screenshot below for the suggestions from google support. google support response

I was expecting to see the add-on to appear in the conference solutions dropdown when creating an event in google calendar.

Contacting the google workspace support further confirmed that using any other language to develop the add-on this won't be visible in the conference solution section in Calendar. The solution is to create the add-on using Apps Script.

The response from google workplace support was:

After checking some details here, I can confirm that if you are using any other language to develop the add-on this won't be visible in the conference solution section in Calendar. The solution is to create the add-on using Apps Script. We have tested this behavior and using the Add-on development in Apps Script is recognized in the calendar web UI.