When looking at the metric Host-name > Properties > Certificate Summary > ESXi Host Certificate > Start/End Date, there may be old or no data
Aria Operations 8.17.2
The metrics for Host > Properties > Certificate Summary > ESXi Host Certificate, come from the SDDC Health Monitoring Solution. While this solution is still available, it will ultimately be deprecated in newer versions.
If you need to view or report the certificate metrics of the ESXi host, use the metrics under Host > Properties > Certificate Summary > Host_name as shown in the screenshot above.