Alert - Test rule

I’m seeing weird alerting - in my graph, I’m charting an azure metric “Healthy Host Count” and it is showing as 20 currently. These are the Azure VMSS instance count. My alert is for when “Healthy Host Count” < 14 and it is alerting. When I hit “Test Rule” it says the metric “Healthy Host Count” value is 13! How do I figure out why alert thinks it’s 13 but the chart is showing 20?