How to get a star rating review snippet

[Strike]

I published a review post about two months ago. I really dislike WP review plugins so I added this code instead:

<script type="application/ld+json">
{
"@context": "http://schema.org",
"@type": "Product",
"name": "[product name]",
"description": "[meta description]",
"brand": {
"@type": "Organization",
"name": "[product manufacturer]"
},
"review": {
"@type": "Review",
"headline": "[article title]",
"author": {
"@type": "Person",
"name": "First Last"
},
"reviewRating": {
"@type": "Rating",
"ratingValue": "4.1",
"bestRating": "5"
}
},
"image": {
"@type": "ImageObject",
"url": "https://site.com/product-photo.png",
"height": 555,
"width": 555
}
}</script>

No matter what I do I cannot get the star rating to stick. The page passes the schema markup/snippets validator, with just some warnings about missing "offers" and the SKU etc.

1. Initially, within a week or two of publishing, the star rating and author displayed properly (persona author attached to most posts on the site, has their own "About the author" box).
2. Then the star rating disappeared, and the author was replaced with "Posted by [website name]" (not the author).
3. Now neither displays.

I have a table at the top of the post with a summary of the product/review, including saying that I gave it 4.1 out of 5. I also state this again in the conclusion. The post is ranking well and I think Google knows it's a review post, it ranks for "[product] review". Do I just need to wait or is there anything I can do?

 

[CCarter]

How old is your domain, your site, and what are your SEO metrics.

If your site is brand new, why would Google trust it? If it is a low quality site, why would Google trust it? If your site has little votes (backlinks), why would Google trust it?

We need some more information, but generally if Google drops the stars after appearing something is off on the site accordingly to them.

 

[Strike]

How old is your domain, your site, and what are your SEO metrics.

If your site is brand new, why would Google trust it? If it is a low quality site, why would Google trust it? If your site has little votes (backlinks), why would Google trust it?

We need some more information, but generally if Google drops the stars after appearing something is off on the site accordingly to them.

3 years, >30 DR, gets plenty of traffic from Google.

 

[CCarter]

"Plenty of traffic" is relative to the individual, look at your competitors who have Stars that stick and compare your metrics to their and see if there is something there.

Edit: 30DR and 3 years is a pretty weak domain. Look at the competitors that have stars sticking though and compare metrics.