Usage information for Metering is not captured for applicaitons that have been running for long periods of time. For example if an application starts when a user logs in, and the user does not turn off or log off the computer for several weeks or longer, usage information is not sent for that application.
Known issue.
This issue has been corrected in version 8.5 RU2. Please upgrade, and upgrade the Application Metering agents to fix the issue.