There is a bug in 2.0.4 of the Help module where it checks where you can move the items to.  For a quick fix run this in the SQL window.

ALTER PROCEDURE {databaseOwner}[{objectQualifier}Help_ListCategoryActiveByParent]

@ModuleID int,
@ParentID int
 
AS
SELECT   [CategoryID],
   [CategoryGUID],
   [Name],
   [Description],
   [Image],
   [KeyWords],
   [ModuleID],
   [Order],
   [Level],
   [Parent],
   [Visible],
   [Deleted]

FROM   {databaseOwner}{objectQualifier}Help_Category

WHERE  [Parent] = @ModuleID AND [ModuleID] = @ParentID
AND   [Deleted] <> 1
AND   [Visible] <> 0

ORDER BY [Level] ASC,
   [Parent] ASC,
   [Order] ASC
   
GO