Grafana - PNP - Services are not populating


We have integrated Nagios core with Grafana using pnp.
We have made all the changes as described by nagios to integrate with grafana. The data source is getting connected. And the host is populating but the services are not populating in the drop down.
Grafana is not showing any errors and no errors in logs as well. We kind of thinking that this is something to do with pnp4nagios. We just wanted to know if there are any place where we can go and check the files for any changes.