Vacation Rules conflicting with 'Owner can approve'

Hi Guys,

Wondering if anyone can explain this?

For standard purchase requisitions in our system, within document types, the 'Owner can approve' flag is not checked. This is because we do not allow requisitioners approver their own document. It must go to somebody else in the team for approval.

One of the approvers was out of office and set up vacation rules for their colleague. This was set to a full 'delegate' so they had all the approvers approval authority. The selected collogue submitted a purchase requisition which fell into the out of office approvers approval authority. As such, an approval notification was sent to them and they were able to self-approve the document. The document was successfully approved.