Topic retention deletes unconsumed messages

A clickstream Kafka consumer group fell behind during a long outage of its downstream warehouse (the consumer was effectively paused for ~14 hours while the warehouse was down). The topic clickstream is configured with retention.ms = 12 hours (cleanup.policy=delete). When the consumer resumes at 08:00, it starts processing again with no errors and no lag alerts clearing the way you'd expect, and reconciliation later finds a ~2-hour window of events that were NEVER delivered to the warehouse, even though the consumer 'caught up.' Dashboards: during resume, the consumer logged OffsetOutOfRangeException on several partitions, and auto.offset.reset=latest. How do you triage and mitigate?