Hi Charlie,
Firstly you need to ensure that these servers have received Windows System Assessment Scan policy and it is enabled. Patch inventory should be sent to NS as soon as windows system Assessment Scan is executed, so you need to execute Assessment scan.
It may be done by different ways:
1. Using schedule defined in Windows System Assessment Scan policy
2. Initiate scan from agent UI - Open Software Delivery tab, select Windows System Assessment Scan policy and click on 'Windows System Assessment Scan' from Application Tasks left pane
3. From Command line using tool AexPatchUtil.exe - tool is usually located on client under "C:\Program Files\Altiris\Altiris Agent\Agents\PatchMgmtAgent\". In order to start Windows System Assessment Scan you need to run command line "AexPatchUtil.exe /i"
4. From NS using default Patch Management task "Run System Assessment Scan on Windows Computers" - Navigate to Jobs and Tasks > System Jobs and Tasks > Software > Patch Management > 'Run System Assessment Scan on Windows Computers'. Select target computers and execute task.
To verify that Assessment Scan has executed check client logs and scan output file STPatchAssessment.xml (STPatchAssessment.xml is usually located at "C:\Program Files\Altiris\Altiris Agent\Agents\SoftwareManagement\Software Delivery\{6D417916-467C-46A7-A870-6D86D9345B61}\cache\"). Output XML should include correct scan date and scan results.
In case if Windows System assessment scan is executed successfully on client but patch compliance report shows inaccurate information, then most likely something is wrong on NS side or by some reason NS does not receive Patch inventory.
Hope this helps,
Roman