channelCustomProperties for Facebbok channel

Summary

Cards are not displayed on Facebbok channel.

Content

I'm using "System.CommonResponse" component to show cards with a description and url action. my problem is that the description displayed is missing some text.

I used the metadata propertie "channelCustomProperties" like in below. 

cardResponse:
    component: "System.CommonResponse"
    properties:
      metadata: 
        responseItems:         
        - type: "cards"  
          cardLayout: "vertical"
          cards:
          - title: "${offers.title}"
            description: "${offers.description}"
            iteratorVariable: "offers" 
            # actions defined here are added to the card.  
            actions: 
            - label: "Details"
              # action type allowable values are: postback, url, share, call, location.
              type: "url"
              payload: 
                url: "${offers.url}"
          channelCustomProperties:
          - channel: "facebook"
            properties:
              top_element_style: "large"