I recently upgraded my Jenkins server from 1.475 to 1.477 and upgraded the installed PTC Integrity plugin from 1.14 to 1.15. After this upgrade the change log for my builds are no longer displaying the author of the change, it just displays "unknown".
I verified that the "Omit Author in Change Log" setting was unselected in the project configuration.
Prior to upgrading Jenkins and the Integrity plugin, the author was being correctly reported in the change log.
Windows Server 2008 R2
Integrity 10 (10.0.0.140), API Version: 4.11.140