Consider the following scenario...
1. Specific events have been disabled or enabled under via View | Administration | Auditing | Audit Events
2. Change Auditor is upgraded
3. The settings under Audit Events area are reverted to default settings
Event class state (enabled/disabled) is not preserved during upgrade and default settings are restored.
Customize the desired event class state (enabled/disabled) following any upgrade.
Waiting fix in a future release of Change Auditor.