It sounds like a similar issue we are currently experiencing.
If you right-click the device in the console and look at "Scheduled tasks and policies" then what is the status of the tasks you are missing in the portal? If it's the issue I'm thinking about then the tasks tend to stay in the "Status: Waiting" and "Result: Not specified" and not in "Status: Delayed" and "Result: The policy has been advertised in the LANDesk software deployment portal" as they should be when successfully shown in the portal.
In case of the above, try saving the attached script to you Management Suite\Scripts folder and create a task from it by right-clicking it within "Manage scripts" in the console and then click "Schedule". Add one of your test devices that experience the issue and run the task. After it ran, do a policy sync and wait a few minutes - then check the portal and "Scheduled tasks and policies" again to see if the status has changed.