Hi,
As it is seen from Your info and screenshots, the client has problems receiving the Plugin Policy - either it is somehow not targeted, or corrupted policy received. Please, try following things, that could help:
1. Restart Altiris Agent on problematic client - and see, if SWU Plugin loaded.
2. Do You have 'Default Filter for Software Update Plugin Policy' filter used in Target 'CIT - Patch Management Test Group'? If so, please change it to some other filter, like 'Windows Computers with Software Update Agent Installed'. Run 'Delta Resource Membership Update' and refresh policies on client after that.
3. If 1. and 2. do not help - we would kindly ask You to attach here client files: Agent.Log, and Client Policy XML, which is located in C:\Program Files\Altiris\Altiris Agent\Client Policy\<server>.xml
Thanks in advance,
Serge