Symptoms

Using Management Worklist, you can redirect worklist items from user A to user B. However, sometimes, the option to redirect is grayed out in Management Worklist.
 

Diagnoses

It is unclear at this point why it was possible to redirect once via the Management Worklist, but not a second time. It should not have been possible at all. There is a chance that the instances were only stopped after the initial redirect, but I do not have that information at this time.
 

Resolution

This is expected behavior. A "stopped" process instance's client task will show in Management Worklist, but not in the end user's worklist. The instance is stopped at the process level, but from a reporting perspective, the activity itself is still "active". However, while the item will show in the Management Worklist, the redirect option should be disabled.