If critical logs are not reaching the SIEM, the most direct root cause is an architectural or configuration failure in the SIEM deployment. A SIEM’s detection capability depends on ingesting the right telemetry from key control points (network, endpoint, identity, cloud). Missing firewall, IDS, and endpoint logs creates blind spots that will prevent detections from firing, even for well-known attacks, because the SIEM simply lacks the required evidence. This commonly happens due to misconfigured collectors/agents, incorrect forwarding rules, blocked network paths, wrong ports/protocols, parsing failures, certificate/auth issues, or incomplete onboarding of data sources. While lack of SIEM knowledge can affect tuning and interpretation, it does not explain missing log delivery. Volume-handling issues typically show up as ingestion throttling, dropped events, or delayed indexing after logs are onboarded—not as a complete absence of critical sources. Performance delays can degrade detection timeliness, but again the scenario states the logs are not reaching the SIEM at all. From a SOC engineering standpoint, the first troubleshooting steps are data pipeline validation (connectivity, agent health, message counts), ingestion dashboards, and source-side forwarding verification. Therefore, improper configuration or deployment architecture is the correct reason.