On 4/12/2018, beginning at 3:00 AM EDT and ending at 10:01 AM EDT, Review Widgets appeared as a blank space. (No errors were shown.)
In early morning EDT, a very brief period of unavailability in one of the data sources for Reviews Widgets triggered a condition that required manual intervention to restore access. Our paging alerts were not appropriately configured to detect this issue, so unavailability persisted until we saw the issue on internal monitoring, when we immediately restarted the affected processes.
We are currently developing a fix that will make Reviews Widgets resilient to this type of condition and have ensured that paging alerts will catch this type of issue in the future.