VERIFIED SOLUTION i
Product Feature: Web Service (API)
When running DeleteDeliveryItem in EngageOne it is not cleaning up failed requests resulting in orphaned deliveryItems that you must run purge against.
Information missing in the database log so the DeleteDeliveryItems operation wasn't aware of what needed to be cleaned up.
ResolutionUPDATED: April 19, 2017
Fixed in all builds of EngageOne later than 184.108.40.206032.70