Google Action prompt link url on Webhook response not working as expected

I am trying to add a prompt link to my Google Action: https://developers.google.com/assistant/conversational/reference/rest/v1/TopLevel/fulfill#link

My response looks like this:

payload.prompt.link = {
  name: 'Open My Website',
  open: {
    url: 'https://mywebsite.com'
  }
}

When testing on my Nest Hub, the link does show as a suggestion on the bottom of the page. However, when I click on it, it simply sends it as an utterance to my Action instead of open the web page.

Any idea why this is happening? And what is the expected behavior for prompt links? I cannot find much documentation on them.

This appears to be the Actions Builder implementation of Link-Out Suggestions, which were not originally available when the Actions Builder was released. They were, however, available for Dialogflow previously.

Link-Out Suggestions require the "WEB_LINK" device capability to work. Smart Displays do not have this device capability.