Query Inspector is a new feature that was added to Grafana v4.5. It shows query requests and responses.
This can be helpful if a graph is not shown or shows something very different than what you expected.
Depending on the data source the response will look different.
The Query Inspector can be found under the metrics tab inside panel edit mode.
First you should check and see if there is anything unexpected or wrong in the query Grafana sends to your database or in the response.
Here there is no graph so I click Query Inspector to open the Query Inspector.
In Query Inspector I can see the query and that it is getting a response. To see the response I can click Expand All or as in this case
datapoints. (Be careful if you Expand All since there can be a lot of data). All the nodes can be opened and closed by clicking on them.
I can now see that data is being returned and the reason I cannot see the graph is that the value is null.
If you think Grafana is showing the data incorrectly then you can open a bug report.
Copy the response by clicking Copy to Clipboard (All the data will be copied wether expanded or not).
Paste it with your question(remove any sensitive data).