How to send a reminder for an acknowledged hold notification?

Summary:

We have setup AP Hold Resolution workflow in such a way that a Received quantity hold is send to the requester. We disabled the possibilty for the requester to release the hold since we require the requester to make sure that the receipt always matches the invoice, so corrective action should be taken in all cases. So, the requester can only acknowledge the notification.

In practice, we see a lot of cases where the notification is acknowledged but the cause of the hold is not resolved. As a result, the invoice stays on hold and does not get paid . We are looking for a way to remand the requester after x days that action should be taken. Obviously, since the Acknowledge action means that the workflow has been completed, so reminder settings in BPM will have no effect. Another option would be to resend the notification when the invoice gets revalidated and the hold is still there, but this does not work either