Schema.org ViewAction button does not work in Gmail

Question

I am trying to create an email with a ViewAction button using schema.org and it does not work. I use the walkthrough on the following page: https://developers.google.com/gmail/actions/apps-script-tutorial . Here's the script:

<script type="application/ld+json">
{
"@context":       "http://schema.org",
"@type":          "EmailMessage",
"description":    "Check this out",
"action": {
"@type": "ViewAction",
"url":   "https://www.youtube.com/watch?v=eH8KwfdkSqU"
}
}
</script>

I looked through all the elements in the script, and it seems to me that they are all used correctly. Therefore, I am at a standstill. Does anyone know what is going on here?

Answer 1

Gmail / google Apps? , , : Gmail "" : Google Apps