Unable to delegate PO Change Order approval from BPM Worklist.

I am able to see PO change order notifications in the BPM worklist under the BPM home page BUT I have a question related to this. I noticed that when a PO change order approval is in progress for a PO, I am unable to search for or the search result does not show the notification for that PO Change order in the BPM Worklist (BPM < Name Drop Down < Home) which means that I am not able to delegate approval for an approver using the BPM notification like I can for a requisition. I need to understand if