Lost Primary Management Server grouping

Hello,

Under Administration > Device Management > Agent Managed I was having the machines grouped by Management servers last week...  now they are not anymore and the "Primary Management Server" Field is not available in the Personalize View for sorting or grouping!!!

What could be the issue?

Thanks,
Dom

System Center Operations Manager 2007 / System Center Configuration Manager 2007 R2 / Forefront Client Security / Forefront Identity Manager