Task "Modified by" and "Started by" fields show the application identity rather than the logged in user.
The customer is running a task but the task "started by" has the service account in the field instead of the user account. The customer is logged in with his account.
ITMS 7.6-8.x
The IIS TaskManagement virtual application had anonymous access enabled
Disable anonymous access on the Taskmanagement virtual application in IIS: