Workflow Messages are Empty when Posting to Mobile App Private Channel

Hi,

I have a workflow setup on my teams private channel. I modified the workflow to post as "User" (otherwise it does not work). I am able to post message to the private channel successfully but the message is empty only on mobile private channels. The messages contain an adaptive card.

I am able to see the message on my desktop application private channels, but not on my Teams mobile app private channels. There is just an empty message display on the mobile app.

Is there any settings that I need to change to fix this? Or should be the payload be different in this case?

This payloads works for desktop private and public channel and mobile public channel. The issue seems to be on mobile app private channel.

{
  "attachments": [
    {
      "contentType": "application/vnd.microsoft.card.adaptive",
      "$schema": "http://adaptivecards.io/schemas/adaptive-card.json",
      "version": "1.4",
      "content": {
        "msteams": { "width": "full" },
        "type": "AdaptiveCard",
        "body": [
          {
            "type": "Container",
            "style": "warning",
            "bleed": true,
            "items": [
              {
                "type": "TextBlock",
                "size": "medium",
                "weight": "bolder",
                "text": "Test title",
                "style": "heading",
                "wrap": true
              }
            ]
          },
          {
            "type": "TextBlock",
            "size": null,
            "weight": null,
            "text": "Test description",
            "style": null,
            "wrap": true
          },
          {
            "type": "FactSet",
            "facts": [
              { "title": "custom:stringKey", "value": "value-string" },
              { "title": "custom:stringSetSingleton", "value": "singleton" },
              {
                "title": "custom:stringSet",
                "value": "forth item, third item, tenth item, sixth item, eighth item, eleventh item, eighteenth item, second item, twentieth item, ninth item, seventeenth item, first item, nineteenth item, seventh item, fo..."
              }
            ]
          }
        ],
        "actions": [
          {
            "type": "Action.OpenUrl",
            "title": "View Item",
            "url": "https://example.com"
          }
        ]
      }
    }
  ]
}