Newbie question for Bind Dashboard & Prometheus

I hope it’s the correct place to ask this, but anyway.
My situation: I have inherited a Grafana/Prometheus installation that was working just fine until some days ago. It’s not in production yet, so I don’t know when, but at some point the Bind Dashboard stopped showing graphs from our Bind Servers.

As far as I understand nobody changed the dashboard and as far as I understand the dashboards do not need any configuration (Please confirm this!).

So, what is the place I should look at in order to find out why the dashboard shows empty graphs (No data points) and the list of hosts is empty?