Grafana alerts - Error:failed to query data: context deadline exceeded


I am fairly new to grafana. I am currently running a dockerized version of Grafana v8.3.1.

I have set up three alerts, all pointing to the same Elasticsearch data source. When I navigate to the “Alert rules” section and expand my alerts folder, I see that the health status of the first alert is “ok”, however, the other two alerts have a “error” status. When I hover over the error, the following message pops up : failed to query data: context deadline exceeded.

I have changed the notification and evaluation timeouts, but this does not seem to make any difference.

The first alert has a classic condition (the one with the ok status), and the other two alerts have a Reduce expression. Not too sure if that makes any difference.

Any help on this will be appreciated.