user87004: I have created a transaction with high miner's fee and it is now in mempool (in testnet):
https://live.blockcypher.com/btc-testnet/tx/abcc4ce473f490896e87102fe3ffb857ff735a0fc97525dadf9c5b0ed5410f9f/
However, it doesn't seem to be confirming. It's already missed two opportunities to confirm. Transactions with much lower miner's fees are going through instead.
Is Bitcoin this random or am I missing something?

user60443: Decoding your transaction shows an output:
"vout": [
    {
      "value": 0.00000000,
      "n": 0,
      "scriptPubKey": {
        "asm": "OP_RETURN 68656c6c6f5f776f726c64",
        "hex": "6a0b68656c6c6f5f776f726c64",
        "type": "nulldata"
      }
    }, ...

This might be the reason the miners won't touch it as it may be flagged as non-standard on older nodes. Notice the warning on blockcypher:

Maybe someone can comment on exactly why, as these null_data transactions were made standard on Bitcoin-core 0.9.0, see https://bitcoin.org/en/developer-guide#null-data

87004: <p>I have created a transaction with high miner's fee and it is now in mempool (in testnet):</p>

<p><a href="https://live.blockcypher.com/btc-testnet/tx/abcc4ce473f490896e87102fe3ffb857ff735a0fc97525dadf9c5b0ed5410f9f/" rel="nofollow noreferrer">https://live.blockcypher.com/btc-testnet/tx/abcc4ce473f490896e87102fe3ffb857ff735a0fc97525dadf9c5b0ed5410f9f/</a></p>

<p>However, it doesn't seem to be confirming. It's already missed two opportunities to confirm. Transactions with much lower miner's fees are going through instead.</p>

<p>Is Bitcoin this random or am I missing something?</p>
 60443: <p>Decoding your transaction shows an output:</p>

<pre><code>"vout": [
    {
      "value": 0.00000000,
      "n": 0,
      "scriptPubKey": {
        "asm": "OP_RETURN 68656c6c6f5f776f726c64",
        "hex": "6a0b68656c6c6f5f776f726c64",
        "type": "nulldata"
      }
    }, ...
</code></pre>

<p>This might be the reason the miners won't touch it as it may be flagged as non-standard on older nodes. Notice the warning on blockcypher:</p>

<p><a href="https://i.stack.imgur.com/QonJE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QonJE.png" alt="Non-standard"></a></p>

<p>Maybe someone can comment on exactly why, as these null_data transactions were made standard on Bitcoin-core <code>0.9.0</code>, see <a href="https://bitcoin.org/en/developer-guide#null-data" rel="nofollow noreferrer">https://bitcoin.org/en/developer-guide#null-data</a></p>
