Census change history: Sync list UI not loading

Census reported a major incident affecting the Census Sync Management UI: the sync list failed to load for some customers, while the sync engine was unaffected. It ran from 2025-06-04 20:11 UTC to 2025-06-04 20:54 UTC (43 min). Census identified a faulty deployment, began reverting it, and implemented a fix before resolving the incident.