Symptoms

Out Of Office Feature not showing tasks of the OOF employee in the Delegated user tasklist
 

Diagnoses

When a new process instance is created, then you can open the work space for the original user and the delegated user and it is visible for both. This is because the workspace has some active filter criteria which are different from the custom worklist.

For custom worklist please refer to the following URL:

http://www.k2underground.com/blogs/johnny/archive/2009/02/26/out-of-office-feature-in-0807-and-the-sourcecode-workflow-client-apis.aspx

Particularly the following:
OpenWorklist method call. To support the OOF items, you need to know utilize the new filters in the WorklistCriteria object to return items that belong to both the work list user and also other users. So if you were doing a custom work list, the code would now look like this:

Dim criteria As New WorklistCriteria
criteria.Platform = “ASP”
criteria.AddFilterField(WCLogical.Or, WCField.WorklistItemOwner, "Me", WCCompare.Equal, WCWorklistItemOwner.Me)
criteria.AddFilterField(WCLogical.Or, WCField.WorklistItemOwner, "Other", WCCompare.Equal, WCWorklistItemOwner.Other)
oWorklist = oConn.OpenWorklist(criteria)
 
 

Resolution
See Diagnoses section.