Criteria of Cancelling PRs in the MassCancel Request

In the MassCancel request, I've defined a new batch to delete some old and unused Purchase Requisitions. The output shows some PRs cannot be cancelled because they are linked to POs and some others are fully in range PRs available to be cancelled. I thought that the criteria of whether it's able to be cancelled or not as they said in the reason column that it's linked to a PO...I've checked some random PRs those fall under the fully in range section and I found that some of them are linked to POs .Yet I'm able to cancel them.