Where I can found backlog size of non-persistent topic?

[ub-3]

I try to get metrics through /metrics API and CLI util, but my subscription size always zero.
The backlog itself is growing, I understand this because of the logs of the consumer, tasks were produced long ago.

[17:34:51] ub-3@host:~ $ curl -s localhost:8080/metrics/ | grep non-per | grep pulsar_subscription_back_log_no_delayed | grep non | grep queue
pulsar_subscription_back_log_no_delayed{cluster="core-production-pulsar",namespace="tenant/core-non-persistent",topic="non-persistent://tenant/core-non-persistent/queue-partition-0",subscription="non-persistent://tenant/core-non-persistent/queue"} 0

[17:35:08] ub-3@host:~ $ sudo -u pulsar /opt/apache-pulsar/bin/pulsar-admin non-persistent stats "non-persistent://tenant/core-non-persistent/queue-partition-0"
{
  "msgRateIn" : 2.360929757908036,
  "msgThroughputIn" : 3205.2719137397426,
  "msgRateOut" : 2.360929842268984,
  "msgThroughputOut" : 3205.272028270798,
  "bytesInCounter" : 20161890,
  "msgInCounter" : 20939,
  "bytesOutCounter" : 19561438,
  "msgOutCounter" : 20281,
  "averageMsgSize" : 1357.6312056737588,
  "msgChunkPublished" : false,
  "storageSize" : 0,
  "backlogSize" : 0,
  "publishRateLimitedTimes" : 0,
  "earliestMsgPublishTimeInBacklogs" : 0,
  "offloadedStorageSize" : 0,
  "lastOffloadLedgerId" : 0,
  "lastOffloadSuccessTimeStamp" : 0,
  "lastOffloadFailureTimeStamp" : 0,
  "ongoingTxnCount" : 0,
  "abortedTxnCount" : 0,
  "committedTxnCount" : 0,
  "waitingPublishers" : 0,
  "nonContiguousDeletedMessagesRanges" : 0,
  "nonContiguousDeletedMessagesRangesSerializedSize" : 0,
  "delayedMessageIndexSizeInBytes" : 0,
  "compaction" : {
    "lastCompactionRemovedEventCount" : 0,
    "lastCompactionSucceedTimestamp" : 0,
    "lastCompactionFailedTimestamp" : 0,
    "lastCompactionDurationTimeInMills" : 0
  },
  "ownerBroker" : "127.0.0.1:8080",
  "msgDropRate" : 0.0,
  "publishers" : [ {
    "accessMode" : "Shared",
    "msgRateIn" : 2.360929757908036,
    "msgThroughputIn" : 3205.2719137397426,
    "averageMsgSize" : 1357.6312056737588,
    "chunkedMessageRate" : 0.0,
    "producerId" : 37435,
    "supportsPartialProducer" : false,
    "metadata" : { },
    "msgDropRate" : 0.0,
    "address" : "/127.0.0.1:63396",
    "producerName" : "core-production-pulsar-195-762",
    "connectedSince" : "2024-10-08T15:33:59.790704634Z",
    "clientVersion" : "Pulsar Go v0.12.1"
  } ],
  "subscriptions" : {
    "sub" : {
      "msgRateOut" : 2.360929842268984,
      "msgThroughputOut" : 3205.272028270798,
      "bytesOutCounter" : 19561438,
      "msgOutCounter" : 20281,
      "msgRateRedeliver" : 0.0,
      "messageAckRate" : 1.8251159675470898,
      "chunkedMessageRate" : 0,
      "msgBacklog" : 0,
      "backlogSize" : 0,
      "earliestMsgPublishTimeInBacklog" : 0,
      "msgBacklogNoDelayed" : 0,
      "blockedSubscriptionOnUnackedMsgs" : false,
      "msgDelayed" : 0,
      "unackedMessages" : 0,
      "type" : "Shared",
      "msgRateExpired" : 0.0,
      "totalMsgExpired" : 0,
      "lastExpireTimestamp" : 0,
      "lastConsumedFlowTimestamp" : 0,
      "lastConsumedTimestamp" : 0,
      "lastAckedTimestamp" : 0,
      "lastMarkDeleteAdvancedTimestamp" : 0,
      "consumers" : [ {
        "msgRateOut" : 2.360929842268984,
        "msgThroughputOut" : 3205.272028270798,
        "bytesOutCounter" : 5823634,
        "msgOutCounter" : 5625,
        "msgRateRedeliver" : 0.0,
        "messageAckRate" : 1.8251159675470898,
        "chunkedMessageRate" : 0.0,
        "consumerName" : "otfuk",
        "availablePermits" : 1375,
        "unackedMessages" : 0,
        "avgMessagesPerEntry" : 1,
        "blockedConsumerOnUnackedMsgs" : false,
        "lastAckedTimestamp" : 1728408984114,
        "lastConsumedTimestamp" : 1728408984335,
        "lastConsumedFlowTimestamp" : 1728408722838,
        "metadata" : { },
        "address" : "/127.0.0.1:9972",
        "connectedSince" : "2024-10-08T16:56:26.596458011Z",
        "clientVersion" : "Pulsar Go v0.12.1",
        "lastAckedTime" : "2024-10-08T17:36:24.114Z",
        "lastConsumedTime" : "2024-10-08T17:36:24.335Z"
      } ],
      "isDurable" : false,
      "isReplicated" : false,
      "allowOutOfOrderDelivery" : false,
      "consumersAfterMarkDeletePosition" : { },
      "nonContiguousDeletedMessagesRanges" : 0,
      "nonContiguousDeletedMessagesRangesSerializedSize" : 0,
      "delayedMessageIndexSizeInBytes" : 0,
      "subscriptionProperties" : { },
      "filterProcessedMsgCount" : 0,
      "filterAcceptedMsgCount" : 0,
      "filterRejectedMsgCount" : 0,
      "filterRescheduledMsgCount" : 0,
      "msgDropRate" : 0.0,
      "durable" : false,
      "replicated" : false
    }
  },
  "replication" : { }
}