If you received a notification advising you have a PO to review for approval and when you log into BeanworksAP you can't find/see it, this is likely because the PO has already been approved by another approver.
For example, the below approval channel states the PO can be approved by either one of the two approvers (Neha or Brittney). If Neha approves/rejects the PO first, then Brittney will not have to review the PO and the PO will not show up in her approval tab as the approval has already been completed by Neha.
The other possibility is that you have a filter turned on, or have unselected some OUs which is why you cannot see the POs. Ensure you have all custom filters turned OFF and all OUs selected in your Approval Tab.