If you ever need to find why something failed to create an alert but you know it was sent by the systems in question. Look at the tables below based on the system of origin.
rap.RapAlertValidationFailure - Searchable by RapAlertId and RapAlertFileId (RapAlert record will be created regardless of whether the alert gets created)
dmc.DmcAlertValidationFailure - Searchable by DmcAlertId and DmcAlertFileId (DmcAlert record will be created regardless of whether the alert gets created)
newitem.NewItemValidationFailure - Searchable by SubBannerId and ProductSkuId (These are found on the NewItemTracking record, NewItemTracking is created regardless of alerts and represents all alerts for stores in the given SubBanner [similar to Retailer]. Failures are stored by StoreId).
coordinator.ResolvedCloningValidationFailure - Searchable by ServiceRequestId that is attempting to be cloned. Failure is rare but possible.