On the trace explorer list view, you can see spans being listed. However, switching to the timeseries view does not show you

The Timeseries (Analytics) view is populated only by indexed spans. To index a specific set of spans you must create a Custom Retention Filter, which writes those spans into the “indexed-spans” store that powers both graphing and trace analytics. Without at least one custom filter that matches the spans you care about, the list view can show them (live search) but the Timeseries view remains empty.

C. The default Intelligent Retention Filter indexes only a small, representative sample and may omit the spans you want graphed; creating a custom filter is still required.

D. Span-to-metric converts spans into regular metrics for dashboards; it is not required for the built-in Trace Analytics graphs.

E. Tags let you slice already-indexed data but do not cause spans to be stored for analytics.

1. Datadog Docs – Trace Search & Analytics > Indexed Spans, para 1 (“Before you can graph or aggregate spans, you must index them by defining a retention filter.”)

2. Datadog Docs – Trace Retention & Ingestion > Custom retention filters (“Create custom filters to index exactly the spans you wish to analyze in Time Series.”)

3. Datadog Docs – Intelligent Retention Filter, same page (“The IRF keeps only a representative subset; define custom filters for additional spans.”)

https://docs.datadoghq.com/tracing/tracesearchandanalytics/traceretentionandingestion/