Unsupported card when using Outlook card sharing of card created with Workflows

Hello,

The full setup is an automation in Confluence that "send a message to teams". It was previously a teams "webhook" connector that have been replaced by a Teams Workflows "send webhook alerts to a channel" from existing templates.

On Confluence side we have configuration for title, message, icon (?) and webhook url.

The workflow works but when using Outlook sharing from the posted card in Teams I get:

Workflows 

Card - access it on go.skype.com/cards.unsupported 

I have have removed Confluence from the equation and used postman to test things.

I was not able to find a way to fix that issue. I noticed there is a advanced card id attribute in "Post card in a chat or channel" but I was not able to find what are legit values.

There is a mention somewhere that adding a subject could help but it doesnt look like it's compatible with the expected "Adaptive Card" configuration in "Post card in a chat or channel".

From what I understand, the workflow just pass the "attachment" structure to the "Post card in a chat or channel" so if the subject is a sibbling element it will obviously not be handled.

Any idea on how to do things right? I would surely expect Workflows to provide an integration that would let us create a simple card compatible with how Teams works so maybe it's just a "simple" bug to be reported somewhere.

Thanks for any help!