There are two reasons why this would occur:
1. Put off the authentication for Printer function
Printer Authentication ON/OFF setting SP5-420-041 OFF(1)/ON(0) Default ON(0)
The user authentication for printer job is disable by setting this SP set to "OFF" (1). This setting has an effectiveness for all print job including standard print app and/or media print app. Because the login request is not issued for any print job.
2. Allowing the server printing
UserTools-SystemSettings-AdministratorTools-User Authentication Management. Printer Job Authentication Entire/Simple(Limitation)/Simple Select "Entire"
Job Permit Setting SP5-490-001 Allowed(1)/Not allowed(0) Default: Not allowed(0)
Please set it to Allowed(1) to available any printer job.
The job will be executed by fixed user name "99999999" by this settings. Then custom authentication app should response "OK" if the login request of the user name is "99999999". An application will have to implement functionality to allow jobs that are process with this user name. Then the application can track and count the network print jobs accordingly.