JSON Crawler fails to crawl product

Hi,
I’m developing an e-com site using snipCart and Nuxt 3.
Site is available to view at grumpy-old-bugger.netlify.app

On the product details page the button data attributes are generated dynamically from the user interacting with the option selectors. My understanding from your doc’s is that this scenario requires product validation via your JSON crawler. I have created an endpoint for the crawler and when provided with the product id this endpoint returns the following:

{
  "id": "pppp",
  "price": 34.68,
  "customFields": [
    {
      "name": "Variants",
      "options": "Black stitching / 4 oz. / S|Black stitching / 6 oz. / S[+2.89]|Black stitching / 4 oz. / M[+1.49]|Black stitching / 6 oz. / M[+6.27]|Black stitching / 4 oz. / L[+2.64]|Black stitching / 6 oz. / L[+7.3]|Black stitching / 4 oz. / XL[+4.02]|Black stitching / 6 oz. / XL[+7.69]|Black stitching / 4 oz. / 2XL[+4.77]|Black stitching / 6 oz. / 2XL[+8.67]|Black stitching / 4 oz. / 3XL[+6.22]|Black stitching / 6 oz. / 3XL[+10.25]"
    }
  ],
  "url": "xx.xxx/products/40-s-mercury-happy-place-t-shirt-red"
}

However, validation still fails with " URL of some products could not be reached. Review domain settings and product URLs. This entry on Order validation might help. See developer console for more details."

Documentation on this feature of snipCart is ‘sparse’ to say the least. A little guidance would be very much appreciated.

TIA