Syntactically Correct Rich Data Not Returning Anything In Google Results Tester

Question

I have a page that contains rich data that validates properly with the Schema.org validator. However, Google reports "No rich results detected in this URL." Can anyone tell me what might cause this?

---

Here is the page JSON:

<script type="application/ld+json">
{
  "@context": "http://schema.org",
  "@type": "VisualArtwork",
  "artMedium": "Digital",
  "artform": "Render",
  "name": "Deep Space",
  "abstract": "Sapceship hall scene",
  "mainEntityOfPage": {
    "@type": "WebPage",
    "@id": "https://www.renderhub.com/gallery/4079/deep-space"
  },
  "url": "https://www.renderhub.com/gallery/4079/deep-space",
  "image": {
    "@type": "ImageObject",
    "url": "https://www.renderhub.com/cadforge/gallery/deep-space.jpg",
    "height": 1280,
    "width": 720
  },
  "dateCreated": "2020-05-31T20:38:43-04:00",
  "dateModified": "2020-05-31T20:38:43-04:00",
  "creator": {
    "@type": "Person",
    "name": "CADFORGE",
    "url": "https://www.renderhub.com/cadforge"
  },
  "thumbnail": {
    "url": "https://www.renderhub.com/cadforge/gallery/deep-space_p.jpg",
    "width": 600,
    "height": 600
  },
  "publisher": {
    "@type": "Organization",
    "name": "RenderHub",
    "logo": {
      "@type": "ImageObject",
      "url": "https://www.renderhub.com/images/rh-logo.png",
      "width": 340,
      "height": 60
    }
  },
  "contentRating": "everyone"
}
</script>

I tried using other validators, as well as re-writing the JSON, with no success.