Grafana OnCall plugins provisioning

I’m trying to enable provisioning for grafana oncall to automatically enable the plugin, but I can’t get it to work. I’m using the following provisioner:

  - type: grafana-oncall-app
    disabled: false
      stackId: 5
      orgId: 100
      onCallApiUrl: "<url>"

However, when I try to access grafana oncall I get an error message saying Could not communicate with OnCall API at null (NOTE: OnCall API URL is currently being taken from process.env of your UI). Validate that the URL is correct, OnCall API is running, and that it is accessible from your Grafana instance.

Is there any way to fix this?

Facing same issue? can some one help here