Anomalies and problems are same thing which are called stories. The only difference between them is that problem has known root-cause (culprit). When an alert is triggered, the anomaly is created and the alert becomes part of the anomaly as an evidence.
The evidences are collected for the story from underneath nodes (on the same transaction path) and when the assisted triage engine finds that the node is a backend. it will mark it as culprit and thus anomaly becomes problem.