Alert Test rule always returns no data

I am using elasticsearch as a datasource and the objective is to plot count of new records added to the index over date histogram.

Graph plot is working flawlessly and shows the data as intended. However, alert rule keeps giving no_data as output.

The weird thing is this whole setup was working fine and has stopped working with no reason.

you have a 1m interval with a very long time range, will return a lot of data points, evaluated every 5s is pretty crazy, every 5m seem more reasonable.

Strange why the query is returning no data. Can you enable debug logging and check the server logs?

1m interval and 5s evaluation is just for debug purpose. I did update to 1h interval that created 24 data points only.

I enabled debug and checked server logs but seems ok except the content length is weird. Log screenshot below:

How have you configured your index name and pattern?