Unable to view Blanket Purchase Order by other user

Hi,

We have found an issue in Purchase Order that, when user raising PO for Blanket type, that specific user can open the PO, but other user cannot open that PO, that Blanket PO is not visible in other user id's list of PO. In normal PO this issue does not exists, for normal PO other user can open any PO regardless of who created it. We want to know the reason behind this, why blanket PO is not visible to other user's. For example, we have attached an screenshot where an example PO is given where user id: KRISHNABRATA.BHATTACHARJYA created