Prometheus queries intermintently returning no metrics

Issue

• Continuously, 50% of the queries returned by Prometheus doesn't have any metrics.

[user@master01 ~]$ export TOKEN=$( oc whoami -t)
[user@master01 ~]$ export URL=https://prometheus-k8s-openshift-monitoring.apps.example.local
[user@master01 ~]$ curl -s -g -k -X GET -H "Authorization: Bearer $TOKEN" -H 'Accept: application/json' -H 'Content-Type: application/json' "$URL/api/v1/query?query=up" | python -mjson.tool
{ "data": { "result": [], "resultType": "vector" }, "status": "success" }