CKpool Solo Pool Ubuntu Difficulty always 0.0

Hi there,

I am running my own BTC node & Solo CKpool on Ubuntu. I have an antiminer s9K with 1 hashboard and have been running since last Christmas. There are no errors in logs, everything looks good just for one thing I am questioning. In the ckpool log, there is the ("diff": 0.0 ) entry in the pool log and it always shows 0.0. Every other entry on the log, updates correctly and on the antminer, everything looks great.

Is it ok that the diff:0.0 is 0.0? See attached logs and highlighted red entries. Also attached is my ckpool config
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[2025-03-12 21:29:12.589] Pool:{"runtime": 1260, "lastupdate": 1741829352, "Users": 1, "Workers": 1, "Idle": 0, "Disconnected": 0}
[2025-03-12 21:29:12.589] Pool:{"hashrate1m": "4.22T", "hashrate5m": "4.96T", "hashrate15m": "4.94T", "hashrate1hr": "14.7T", "hashrate6hr": "13.8T", "hashrate1d": "6T", "hashrate7d": "3.35T"}
[2025-03-12 21:29:12.589] Pool:{"diff": 0.0, "accepted": 2769230635, "rejected": 707625, "bestshare": 1701820452, "SPS1m": 0.255, "SPS5m": 0.31, "SPS15m": 0.347, "SPS1h": 0.418}
[2025-03-12 21:29:18.062] Stored local workbase with 4820 transactions
[2025-03-12 21:29:52.872] Stored local workbase with 4809 transactions
[2025-03-12 21:30:12.594] User bc1qsc:{"hashrate1m":"3.97T","hashrate5m":"4.77T","hashrate1hr":"14.6T","hashrate1d":"6.44T","hashrate7d":"3.3T","lastshare":1741829400,"workers":1,"shares":1638890517,"bestshare":691603928.27803731,"bestever":691603928,"authorised":1739747080}
[2025-03-12 21:30:12.595] Pool:{"runtime": 1320, "lastupdate": 1741829412, "Users": 1, "Workers": 1, "Idle": 0, "Disconnected": 0}
[2025-03-12 21:30:12.595] Pool:{"hashrate1m": "3.23T", "hashrate5m": "4.56T", "hashrate15m": "4.8T", "hashrate1hr": "14.5T", "hashrate6hr": "13.7T", "hashrate1d": "6T", "hashrate7d": "3.35T"}
[2025-03-12 21:30:12.595] Pool:{"diff": 0.0, "accepted": 2769269245, "rejected": 707625, "bestshare": 1701820452, "SPS1m": 0.195, "SPS5m": 0.284, "SPS15m": 0.336, "SPS1h": 0.414}
[2025-03-12 21:30:23.062] Stored local workbase with 4755 transactions
[2025-03-12 21:30:57.877] Stored local workbase with 4715 transactions
[2025-03-12 21:31:12.600] User bc1qsc:{"hashrate1m":"5.58T","hashrate5m":"4.98T","hashrate1hr":"14.5T","hashrate1d":"6.44T","hashrate7d":"3.3T","lastshare":1741829464,"workers":1,"shares":1638975459,"bestshare":691603928.27803731,"bestever":691603928,"authorised":1739747080}
[2025-03-12 21:31:12.601] Pool:{"runtime": 1380, "lastupdate": 1741829472, "Users": 1, "Workers": 1, "Idle": 0, "Disconnected": 0}
[2025-03-12 21:31:12.601] Pool:{"hashrate1m": "4.86T", "hashrate5m": "4.82T", "hashrate15m": "4.88T", "hashrate1hr": "14.4T", "hashrate6hr": "13.7T", "hashrate1d": "6T", "hashrate7d": "3.35T"}
[2025-03-12 21:31:12.601] Pool:{"diff": 0.0, "accepted": 2769354187, "rejected": 707625, "bestshare": 1701820452, "SPS1m": 0.293, "SPS5m": 0.298, "SPS15m": 0.337, "SPS1h": 0.413}

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Ckpool config

ckpool@zzy:~/solobtc$ more ckpool.conf
{
"btcd" : [
{
"url" : "127.0.0.1:8332",
"auth" : "rpc_admin",
"pass" : "",
"notify" : true
}
],
"btcsig" : "/xxxxxxxxxx/"
}