Alert in workflow not sent until another alert is created


I have a workflow set up for a Purchase Order Requisition that flows through several approvals. The last step of the workflow is that an Alert is sent to the submitter stating the Purchase Order Requisition is fully approved and assigned a Purchase Order Requisition number.

The problem is that the final alert is not being sent until the next alert is queued. All other actions in the flow are immediate. The workflow is set to trigger immediately.

Any insights?