Supplier Acknowledgment Workflow is not sending for Supplier Portal Users

Summary:

We are standing up the Supplier Portal and in the process of testing. The one piece we cannot figure out is how to get the Purchase Order Acknowledgement to send to the supplier's email. The Purchase Order goes into the Pending Supplier Acknowledgment successfully, but then nothing is sent. I can see the acknowledgement in the Supplier Portal. We have supplier communication turned on and am I getting a rejection notification of the acknowledgement, but am not receiving the initial first email stating that the acknowledgment is ready. I can see that is follows this task configuration called: DocumentAcknowledgmentRequestForAction