Using APM Alerts flow fail to trigger when configured for metrics that return rational numbers (decimals/floating-point values, e.g., 0.1, 1.9). This frequently occurs with metrics ingested from external sources like Prometheus.
This is a known limitation within the APM alerting backend.
A permanent fix to introduce full support for rational numbers in the APM alert flow has been developed and will be deployed in the next upcoming DX SaaS update (26.4.1) and next on-premise release (27.1).