Active requests not having Phase count

@vsr1 @Marco_Greco
while calling /admin/active_requests api , i get a response like

{
    "elapsedTime": "3.133659173s",
    "executionTime": "3.133605382s",
    "phaseCounts": {
        "fetch": 22032,
        "primaryScan": 22523
    },
    "phaseOperators": {
        "authorize": 1,
        "fetch": 1,
        "primaryScan": 1
    },
    "requestId": "128d35dc-17b7-42b2-aae2-f473d0306a9e",
    "requestTime": "2020-10-08 10:33:07.418196981 +0000 UTC",
    "scanConsistency": "unbounded",
    "state": "running",
    "statement": "SELECT country FROM `travel-sample` WHERE `travel-sample`.country <> \"France\"",
    "users": "Administrator"
}

I saw few cases, where for few requests there was no phase Count.
I want to understand, as in for which all cases, phase count sub map will be absent?

PhaseCounts only appear when operators retrieve documents - you may have caught the active request before it actually produced document keys or fetched documents.

Thanks for the explanation @Marco_Greco