maybe this helps
Go to filters - computer filters, right click on "All local agent managed computers" and select clone. Pick new name for your edited filter. I usually put our company name in front of mine so I know I created the new custom filter.
Then go to edit, changed query mode to Raw SQL.
Changed [is Managed] to = 0 and also took out a few lines to end up with this under Parameterised Query which seemed to work for me.
SELECT
[vri1_Computer].[Guid],
[vri1_Computer].[Name]
FROM
[vRM_Computer_Item] AS [vri1_Computer]
WHERE
(
(
([vri1_Computer].[IsManaged] = 0)
)
)