At 5:52AM Eastern Time Zone, it was discovered that editing a scheduled campaign following a specific sequence of steps resulted in the removal of the targeted audience.
By 6:11AM Eastern Time Zone, the issue had been identified, fixed, and confirmed. Service was permanently restored.
A post-mortem was conducted and revealed that the root cause was a breakdown in the hand-off communication between Development and DevOps. As a result, a recent upgrade to the user interface pushed to production that morning was missing a key component.
The corrective action is as follows: 1. The development team will now explicitly mention the type of deployment in their request. 2. A standard deployment request checklist is being developed which will make the process even more transparent and easier for the Development and DevOps teams to fully communicate all necessary updates for each production deployment.