Prometheus 'equal' comparison binary operator makes labels disappear in Grafana legend

Hi everyone

I’m trying to detect no activity in one of my Gauges in Prometheus using the delta() function. Briefly, if the gauge does not show a change from its value 5 minutes ago - I consider it to be inactive. The query I’m using is thus simply this:

min(delta(metric_name{}[5m])) by (label_name) == 0

However, the graph presented does not show labels in the legend:

Contrast that with the ‘<=’ comparison binary operator:

The same goes for the ‘>=’ comparison binary operator.
Why am I losing series’ labels when I use ==?


Weirder yet: hovering over the == graph always presents the current timestamp and not the time in the x-axis :confused:

This seems like a bug in Grafana, and the hovering time issue may explain why there is no legend or table with values :thinking: