"No data in response" on Grafana charts

OH 2.5.12 on RPi 3B+
Grafana v8.1.3
InfluxDB 1.8.9

Few screenshots attached.

I uninstalled both influxdb and grafana and reinstalled both from scratch on 9-10-2021. Influxdb and grafana was working perfectly. From last night I saw that the charts were flat for several hours, which means it wasn’t getting any data. In an openhab rule, the following returned false (sensor item not updated in last 60 mins):

logInfo("Notification", "v2_htc_111_rh updated in last 60 min(s): " + v2_htc_111_rh.updatedSince(now.minusMinutes(60)))

However, in logviewer I can clearly see that the sensor is being updated every few seconds. And grafana chart showed “No data in response”:

I restarted the RPi, the “No data in response” message is gone but there’s just 2 dots on the chart (please see screenshot):
dotOnChart

and the following log shows true, like it should:

logInfo(“Notification”, "v2_htc_111_rh updated in last 60 min(s): " + v2_htc_111_rh.updatedSince(now.minusMinutes(60)))

I have checked the data source in grafana and it still shows “Data source is working”:
DataSourceIsWorking

Can someone please help me with this? It worked perfectly for 2 days before encountering this issue. Any help would be much appreciated.
last2days

Update:

I had followed this tutorial:

https://community.openhab.org/t/influxdb-grafana-persistence-and-graphing/13761/86

and created 3 users for influxdb: admin, openhab, grafana. In services/influxdb.cfg, I changed the user from openhab to admin, and rebooted the RPi. It turns out that the grafana charts are back up. I hope this helps someone who’s facing this or similar issue. This is the first time that I had used the admin user. On all my other RPis, I am using the openhab user and both influxdb grafana are working fine.

This seems to be a work around this issue for now. If anybody can give any insight on this issue, it would be much appreciated. Thanks!