Can't link Loki to a dashboard!

Hi,

I’m just starting out with Loki, and I have no problem adding a dashboard with a grid and pulling the row data back with Loki datasource.

However, I cannot seem to find a way of driving a graph from an aggregation off the Loki data.

I then tried setting up a Prometheus source, pointing to the Loki endpoint on server:3100/loki, and this just gives me a Loading Metrics, and that is all.

Is there something simple I am missing here, or is something broken?