I found that Grafana Loki has a huge delay on displaying logs with custom timestamp if the custom timestamp is older than 2 hours from “now”.
So just wait like 3 hours then check again in the UI. If it didn’t work you can restart Loki and wait another 3 hours.
I am running Grafana Enterprise, Loki & Promtail in Ubuntu 18 Virtual Machine.
You can do dry run as below to verify the promtail config is parsing the labels & timestamp properly. Make sure you are in same dir as promtail-linux-amd64 when running that, and promtail is set to scrape /sample.log.
cat /sample.log | ./promtail-linux-amd64 -config.file=promtail-local-config.yaml --stdin --dry-run