user6097: Hello and thank you beforehand for your time! I read a lot before posting and could not find a solution to this.
Pool.pm is complaining about the metadata '721' throwing an error: "Expecting an OBJECT with a field named 721"
I first thought I made the transaction using a different policy id than the metadata like in this post: NFT Image not Displaying in Pool.pm after using the 721 Metadata Standard
But as you can see from https://cardanoscan.io/transaction/c02c4db6bc9b2b9f3adcac930559368f7c2a4f00a2a53fc8661fae3b5ce844b2?tab=metadata the policy id matches the one on the metadata. The metadata I used is:
{
  "777": {
    "prc": "0.5",
    "addr": [
      "addr1q8pfw723tpkt8hl7q4wxx7h9seqt4cy22zrqk4axmhmcglwykt772jcyu6u",
      "9pv84nktsmpefeh7w9y6hdr87a65a93ysut2t0r"
    ]
  },

  "721": {
    "3e3a9f39933d04bd854527801f615d35d1cbe1b0344d482af20343ae": {
      "ShaveandTattooed": {
        "Name": "Shave and Tattooed",
        "Artist": "Marvin Lunas",
        "Image": "QmRTJUU8MUw5rUzES6XJd5RiA55K9seVAWU3tTkS8UoQYi",
        "mediaType": "image/png",
        "Description": "Description",
        "files": [
          {
            "mediaType": "image/png",
            "src": "QmUhgW6c8MKmzZKMNtr8Sfvb8UjqM3bgCh6X1upDCNAgHH",
            "Name": "Shave and Tattooed"
          }
        ],
        "ID": "1",
        "Minting Platform": "https://adamagic.io"
      }
    },
    "Version": "1.0"
  }
}

I have no idea what is causing this issue because I did use the same template before and it was all good.
It also has a problem while loading the thumbnail and at this point, I think the problem is on me.
Once again, thank you all for your time and effort!
Cheers

user4627: It's showing up for me alright on pool.pm: https://pool.pm/asset1xpdk028mq57te9dkg62rvy79nv2mhl4zr78xgn
Might have been just a temporary issue while data was populating?
There's a testing tool here, that you can use to verify it works: https://pool.pm/test/metadata
Here it's populated with your metadata: Link
When you remove or rename the "721" object you'll see your exact error show up: "Expecting an OBJECT with a field named 721".
So if this is the place you're seeing it, there might be just a simple syntax error in the json you're putting in here.
Just some potential minor improvements to the metadata:
According to the spec at https://cips.cardano.org/cips/cip25/#specification you should use lowercase attribute names like "name" and "image" instead of "Name" or "Image".
And for the image hashes I'd add "ipfs://" as a prefix to make it more clear where to look for them, but it does usually work fine without.
Anyways looks like it all works fine on my side as is 

6097: <p>Hello and thank you beforehand for your time! I read a lot before posting and could not find a solution to this.
Pool.pm is complaining about the metadata '721' throwing an error: &quot;Expecting an OBJECT with a field named <code>721</code>&quot;</p>
<p>I first thought I made the transaction using a different policy id than the metadata like in this post: <a href="https://cardano.stackexchange.com/questions/2006/nft-image-not-displaying-in-pool-pm-after-using-the-721-metadata-standard">NFT Image not Displaying in Pool.pm after using the 721 Metadata Standard</a>
But as you can see from <a href="https://cardanoscan.io/transaction/c02c4db6bc9b2b9f3adcac930559368f7c2a4f00a2a53fc8661fae3b5ce844b2?tab=metadata" rel="nofollow noreferrer">https://cardanoscan.io/transaction/c02c4db6bc9b2b9f3adcac930559368f7c2a4f00a2a53fc8661fae3b5ce844b2?tab=metadata</a> the policy id matches the one on the metadata. The metadata I used is:</p>
<pre><code>{
  &quot;777&quot;: {
    &quot;prc&quot;: &quot;0.5&quot;,
    &quot;addr&quot;: [
      &quot;addr1q8pfw723tpkt8hl7q4wxx7h9seqt4cy22zrqk4axmhmcglwykt772jcyu6u&quot;,
      &quot;9pv84nktsmpefeh7w9y6hdr87a65a93ysut2t0r&quot;
    ]
  },

  &quot;721&quot;: {
    &quot;3e3a9f39933d04bd854527801f615d35d1cbe1b0344d482af20343ae&quot;: {
      &quot;ShaveandTattooed&quot;: {
        &quot;Name&quot;: &quot;Shave and Tattooed&quot;,
        &quot;Artist&quot;: &quot;Marvin Lunas&quot;,
        &quot;Image&quot;: &quot;QmRTJUU8MUw5rUzES6XJd5RiA55K9seVAWU3tTkS8UoQYi&quot;,
        &quot;mediaType&quot;: &quot;image/png&quot;,
        &quot;Description&quot;: &quot;Description&quot;,
        &quot;files&quot;: [
          {
            &quot;mediaType&quot;: &quot;image/png&quot;,
            &quot;src&quot;: &quot;QmUhgW6c8MKmzZKMNtr8Sfvb8UjqM3bgCh6X1upDCNAgHH&quot;,
            &quot;Name&quot;: &quot;Shave and Tattooed&quot;
          }
        ],
        &quot;ID&quot;: &quot;1&quot;,
        &quot;Minting Platform&quot;: &quot;https://adamagic.io&quot;
      }
    },
    &quot;Version&quot;: &quot;1.0&quot;
  }
}
</code></pre>
<p>I have no idea what is causing this issue because I did use the same template before and it was all good.
It also has a problem while loading the thumbnail and at this point, I think the problem is on me.</p>
<p>Once again, thank you all for your time and effort!
Cheers</p>
 4627: <p>It's showing up for me alright on pool.pm: <a href="https://pool.pm/asset1xpdk028mq57te9dkg62rvy79nv2mhl4zr78xgn" rel="nofollow noreferrer">https://pool.pm/asset1xpdk028mq57te9dkg62rvy79nv2mhl4zr78xgn</a></p>
<p>Might have been just a temporary issue while data was populating?</p>
<p>There's a testing tool here, that you can use to verify it works: <a href="https://pool.pm/test/metadata" rel="nofollow noreferrer">https://pool.pm/test/metadata</a></p>
<p>Here it's populated with your metadata: <a href="https://pool.pm/test/metadata?metadata=%257B%2522721%2522%253A%257B%25223e3a9f39933d04bd854527801f615d35d1cbe1b0344d482af20343ae%2522%253A%257B%2522ShaveandTattooed%2522%253A%257B%2522Name%2522%253A%2522Shave%2520and%2520Tattooed%2522%252C%2522Artist%2522%253A%2522Marvin%2520Lunas%2522%252C%2522Image%2522%253A%2522QmRTJUU8MUw5rUzES6XJd5RiA55K9seVAWU3tTkS8UoQYi%2522%252C%2522mediaType%2522%253A%2522image%252Fpng%2522%252C%2522Description%2522%253A%2522Description%2522%252C%2522files%2522%253A%255B%257B%2522mediaType%2522%253A%2522image%252Fpng%2522%252C%2522src%2522%253A%2522QmUhgW6c8MKmzZKMNtr8Sfvb8UjqM3bgCh6X1upDCNAgHH%2522%252C%2522Name%2522%253A%2522Shave%2520and%2520Tattooed%2522%257D%255D%252C%2522ID%2522%253A%25221%2522%252C%2522Minting%2520Platform%2522%253A%2522https%253A%252F%252Fadamagic.io%2522%257D%257D%252C%2522Version%2522%253A%25221.0%2522%257D%252C%2522777%2522%253A%257B%2522prc%2522%253A%25220.5%2522%252C%2522addr%2522%253A%255B%2522addr1q8pfw723tpkt8hl7q4wxx7h9seqt4cy22zrqk4axmhmcglwykt772jcyu6u%2522%252C%25229pv84nktsmpefeh7w9y6hdr87a65a93ysut2t0r%2522%255D%257D%257D" rel="nofollow noreferrer">Link</a></p>
<p>When you remove or rename the &quot;721&quot; object you'll see your exact error show up: <em>&quot;Expecting an OBJECT with a field named <code>721</code>&quot;</em>.</p>
<p>So if this is the place you're seeing it, there might be just a simple syntax error in the json you're putting in here.</p>
<p>Just some potential minor improvements to the metadata:</p>
<p>According to the spec at <a href="https://cips.cardano.org/cips/cip25/#specification" rel="nofollow noreferrer">https://cips.cardano.org/cips/cip25/#specification</a> you should use lowercase attribute names like &quot;name&quot; and &quot;image&quot; instead of &quot;Name&quot; or &quot;Image&quot;.</p>
<p>And for the image hashes I'd add &quot;ipfs://&quot; as a prefix to make it more clear where to look for them, but it does usually work fine without.</p>
<p>Anyways looks like it all works fine on my side as is </p>
