Dashboards not showing metrics from APM side:
1. OOTB UMA Cluster (and other): SuperDomain\|${Cluster:regex}\|.*\|Infrastructure Agent.*
2. real-world metric (exampe): SuperDomain|aiops|ServerName|Kubernetes Agent|Kubernetes|Namespaces:Number of CPU
This is being caused due to the field in "Expression"
Adjust "Expression" field to the following variable:
Name: SourceProduct
Values: APM
It will match with APM indexes.