Filtering by variable removes label

I am creating a dashboard to display prometheus queries of node-exporter(s) and display the up/down status of various nodes.
I have created Grafana variables to filter the resources to be displayed. I am using the ‘Gauge’ visualisation to display whether the node is up or nt The issue is that when filtering the label value under the gauge dissappears.

The query (identical in both):
up{instance=~"$Instance",job="Job name"}

This fixed itself when I started monitoring more than two instances.